I'm traveling at the moment, so I'd like to contribute to what I've seen/visited so far.
Chicago, Illinois
O'Hare International Airport - The "no wild pokemon" condition applies here, as you can only find Pokemon in Lures. O'Hare has five gyms, and there are a ton of PokeStops (99% of them are lured), and be ready to find some rare Pokemon if you are inside two or more lures.
San Diego, California
Balboa Park/San Diego Zoo - This area gets lit every day. Great place to hunt for Pokemon, and find several farms.
San Diego International Airport - Not as big as Houston's airport or Chicago's airport, but you will find a few Pokestops inside each terminal. However, the nearest gym is actually outside the airport.
Otay Mesa - This area, located above the Tijuana/San Diego border, has several schools as gyms which I find a little unusual.
Imperial Valley, California
Bucklin Park - I was told that this park is the only area in the region that gets lit up with lures every day. There is one gym that is a Level 10 which makes it impossible for teams to take it down (It's Valor at the moment lol).
Downtown El Centro - Two gyms are located on Main Street (Post Office and City Hall), as well as several Pokestops located in historic buildings (such as the old Library) and monuments.
Ensenada, Mexico
Zona Turistico - This area is perfect for walking, and farming water type Pokemon. There are a couple of gyms on Lazaro Cardenas Avenue as well as Pokestops (lots of them, mostly in restaurants).
Puerto de Ensenada/Malecon - Lots of rare "dex-fillers" can be found here, especially water and poison types. Plus, there is free wifi in that area.