Just stayed at Suites Bahia. It is downtown, right on the waterfront at Calle 3. It is an older place, but I found the room to be very large - it had a king and a queen bed, a small kitchen area with a full sized refrigerator, a full size walk in shower, a storage closet, remote control TV and AC. The housekeeping was very good - the room I had was exceptionally clean. There is a computer in the lobby you can use to access the internet at no charge - sorry no printer.
Location is in heart of town - however no beach.
This is a real budget place - I got my room as part of a air package so I don't know exact cost, but I'm guessing their standard room is about $50 - $60 a night.
Casa Mexicana is a block or so to the South. Very new and much nicer in terms of amenities. There is a nice sun deck and a small pool as well as a nice public eating area. Rooms are relatively small (1/2 to 1/3 the size) when compared to Bahia, but much newer. Rooms here are at least double those at Bahia.
Good luck.
OC