Boeing 737-300 (Shuttle)
The 737-300 Shuttle is mainly used for flights to medium size markets from the four hubs in San Francisco, Denver, Chicago O'Hare and Washington Dulles.
There are two different configurations. A little more than half of the planes are equipped with Economy Plus. But these ones are former Shuttle aircraft and offer significantly less service. While you can find out what version United plans to use for your flight, these plans do often change even a few hours before departure.
Acceptable First seats with fairly little legroom.
Seats 2A, 2D
Best First seats on this plane.
Seats 2B, 2C
Decent First seats. Sadly your legroom is reduced by a metal frame under the seat in front of you.
Row three offers pretty good legroom, particularly on the starboard side.
Seat pitch is approximately 30-31 inches.
Seats 9A, 9F
These seats don't exist, if you get switched over to the Economy Plus version of the 737-300.
Seats 23D, E, F
The recline of these seats is limited.
On the one hand these seats offer some extra space and a two seat row that some couples enjoy. However, they are located right between the galley and teh lavatory, which can be a nuisance. Decide for yourself.