Depending on the weather, I'd stay south as much as possible this time of year plus, the more south you go, the more access to the southwestern and Mexican cuisines - each area is different - Texas has a different taste from New Mexico, from Arizona, from CA. San Diego is beautiful this time of year - like most of CA due to the fact there isn't much of a marine layer until May/June.
I've found the Mexican food in New Mexico to be fairly spicy hot - I would use New Mexico dried peppers for my tamale sauce. If you go through Tucson, there is a Mexican restaurant I love: Cafe Poca Cosa. Its actually Oaxacan food. The restaurant is a bit pricey and mood oriented, but the food is AWESOME. You order a meat type and then they serve you beans, greens, salsa and homemade tortillas to 'roll your own.' They usually have differnt types of moles for the meat sauces - green mole, red mole...you get the picture. Additionally, they have great margaritas (I like mine on the rocks with salt). They are located in downtown Tucson.
Event though I grew up in Phx, I don't go there very often anymore cuz I don't recognize the place. Too big.
When I lived in San Diego, I used to go to a Mexican place which had a tortilla making factory right next to it - it was in the Hillside district (near the airport). They had pretty good Mexican food. San Diego also had a very tasty dessert place up on the hill overlooking the downtown area - just looked it up - Karen Krasne's desserts - oh my, a Cordon Blue chef and amazing cooieis, cakes and pastries.
This is a long shot, but if you play badminton, San Diego has a thriving badminton community that meets many times during the week at the Balboa Activity Center in Balboa Park - tons of courts and lots of very good players.
I also used to run on the beach - Mission Beach. La Jolla is pricey but beautiful. San Diego (as I remember it) was a great place to live - loved it.
Have a great time! I love these types of road trips - right now I'm freezing my a$$ off in Germany and I do miss my Mexican food, oh, boy do I. Serious case of envy right now towards you
