Air-King: The Air-King could be considered the "entry level" model from Rolex. Current models retail for $3200 with the smooth bezel fitted, or $3250 with the engine turned bezel. It is 34mm in diameter and comes with an Oyster bracelet by default. The Air-King does not have a Date. In the 1970s, the Air-King was offered with a date (scarce!) and in gold & steel combinations. Those two variations likely ceased production since they are redundant next to the Date and Oyster Perpetual models.

Date: The Rolex Date is 34mm like the Air-King, but it obviously includes a date function.  IIts production began in the late 1950s around the time the steel Datejust was introduced. Retails range from $5,250 with a smooth bezel and Oyster bracelet to $7,000 with an 18K white gold fluted bezel and diamond markers, to $15,050 for 18K Yellow gold on a jubilee bracelet.  The date model was once offered in 3 flavors: steel, 18k yellow & steel, and all 18k yellow gold.   It is now only available in steel or solid yellow gold.

Datejust: The Datejust is the best selling Rolex model on the market, and has been for decades. It was first introduced in 1945. The gents model is 36mm in diameter and typically came on a Jubilee bracelet. Rolex seems to have changed their tradition on this, and is sending more Datejust models out the door with the Oyster band. Models with smooth bezels exist, but are more scarce. Most have the fluted bezel, which is 18k white gold on the steel model.

The Datejust was only available in gold until 1957 (conveniently a year after the release of the Day-Date which still has never seen a steel model). The steel Datejust was introduced and became an instant success. Rolex soon saw the steel variations selling much quicker than their gold models. Rolex countered this in 1962 when they introduced the gold and steel version.. - Current Datejust Selection

Ladies Date/Datejust: These two models use the same 26mm case mold and offer the exact same functionality. Rolex discontinued the ladies Date, there was so much overlap in the models that it seemed long overdue.   Retails range from $5150 for the most current 171960 steel Datejust.  The more popular Datejust with White gold bezel retails for $6,000.  The Gold & Steel models start at $7150 (179173) and go up to $12,375 for a 179313 with diamond mother of pearl dial and 12 diamond bezel.

Explorer: It was introduced in 1954, and has had one look through-out its life; a black dial with Arabic numbers at 3', 6' and 9', no date, smooth bezel, Oyster bracelet, and a stainless steel 36mm case. Except for the updates that all Rolex watches have received, it remains essentially the same watch. Today the watch retails for $4,925.

Explorer II: This model was introduced in the early 70's and was never widely distributed or popular until 1991. The original model was produced until the current model was released in 1985. The Explorer II uses the same movement as the GMT-II models and makes use of a secondary 24-hour hand that rotates once every day. The engraved steel bezel is stationary and was originally designed for speleologists (cave explorers) who can have a hard time determining if it is am or pm. Today it retails for $5925 and comes with only one choice: a black or a white dial. - Current Rolex Explorer Selection

Oyster Perpetual: An odd name for a model considering every Rolex mentioned on this page is also an Oyster Perpetual... By itself, the "Rolex Oyster Perpetual" was basically the same as the smaller 34mm Air-King model.  The Current Oyster Perpetual (no-date) is now the same size as the Datejust and comes only in steel or steel with white gold bezel.  Rolexhas introduced several unusual dials for this model.   Retails start at $4,000 for the simplest ladies Oyster Perpetual and $4,400 for the simplest men's Oyster Perpetual. Both come standard with an Oyster bracelet. - Current Oyster Perpetual Selection

Submariner: The Submariner was introduced by Rolex in 1954. The watch comes only on an Oyster bracelet and has a 40mm case. The steel model is only available with a black dial. It has the common single direction rotating bezel with minute markers for the first 15 minutes. The original models until 1958 are often considered "James Bond" models and have some easily recognizable difference. Primarily, they had a smaller crown, no crown guard, and the bezel only had minute markers every 5 minutes. In the late 70s the model 16800 was introduced. It sported the new sapphire crystal and quick-set function. In 1989, the current 16610 was introduced with a improved movement and a more secure bezel. The Submariner is one the most popular models and comes in 4 styles, $5,450 for steel (no date), $6,000 for steel (with date), $9,300 for 18k & steel, and $25,250 for the all gold model, the new ceramic bezel all gold model retails for $27,250 in yellow gold or $29,850 in white gold.  Rolex will be bringing the ceramic bezel to the 18K & Stainless Submariner in 2009 . - Current Submariner Selection

Sea Dweller: The Sea Dweller was introduced in 1971 and discontinued in 2008. It is virtually the same watch as the Submariner. The only real differences are the thicker and heavier steel case, thicker crystal with no cyclops eye, and the helium escape valve useful only to deep divers. The original model was rated for 2000 feet and called the "Rolex Submariner 2000 Sea Dweller". It lost the "Submariner 2000" part of the title in 1973. The current issue, model 16600, is rated to 4000 feet and is sold only in steel for a $6,400 retail.  The Sea-Dweller DEEPSEA, model 116660, has replaced the Sea-Dweller model 16600 and retails for $9,250.  The DEEPSEA model offers a greater depth rating (to 12,800 feet) along with a thicker, larger case and an improved "Glidelock" buckle

GMT-Master: The 1950s were an exciting decade for Rolex and included the introduction of the classic GMT- Master. It was one of the first watches to utilize a second hour hand to indicate a second time zone. With the simple rotating 24 hour bezel, one could fairly easily tell the time in any time zone. The late 70s saw the introduction of the GMT-Master II which was basically the same, except now the user could easily adjust the 2nd hour hand with the crown in position 2. The steel models are only offered with black dials. The bezels are available in all black, red/ black, or red / blue. GMT's typically come with a Jubilee bracelet installed.

The original GMT-Master (16700) was phased out in the late 90s. The latest serial number Bernard's had for the 16700 was a U#, putting its birthday around 1997. With the flood of new models with a second time zone function from other manufactures, retiring it was a smart move, as most consumers will want to adjust the 2nd hour hand.
 

The GMT-Master II (16710) was discontinued in 2008 and replaced with the GMT-Master II (116710) The primary difference besides the 3186 caliber movement with Parachrom Bleu hairspring is the ceramic (Cerachrom) bezel.  Some late production 16710s have been discovered with the 3186 movement.
 

The GMT-Master II retails for $7,000 iin steel, $10,350 in steel & gold, and $25,550 for solid gold.  - Current GMT-Master Selection

Daytona / Cosmograph: The story of the Rolex Cosmograph could be called the most chaotic of all the Rolex Oyster models. Rolex is keen on creating a winning product. The watch never really got off the ground until 1986 when the market for them exploded and the watches would often sell for double the retail price in Italy. The "Paul Newman" models manufactured around 1967 were and still are the most desirable of the Daytona models fetching prices over $30,000. It retailed for around $150 back then. In 1989, Rolex replaced the Valjoux workhorse movement with the Zenith El Premiro movement. During the 1990s, the Daytona was the only Rolex model not using a Rolex movement. In 2000 came the newly developed Rolex caliber 4130 with a 72 hour power reserve. The steel 116520 retails at $9,925. S&G for $14,250 . $28,100 for 18k yellow gold.  Steel Daytona's have consistently sold for more than retail since the 1980s. The two-tone and gold models aren't treated with the same regard and discounts can be found. Current Daytona Selection