Spending the long weekend in Phoenix and area - Tempe
You can certainly stay within downtown Tempe, avoid co-ed crowds (mostly), and eat and drink well. Definitely head to House of Tricks for lunch or dinner. Menus change with the season, the food is inspired, and the leafy patio is lovely, though you may want a seat within the converted bungalow (it's still pretty darn hot). Mucho Gusto is a great, if a little noisy, destination for Mexican; the chicken mole was delish last I ate there. La Bocca pizzeria is right on Mill Avenue, Tempe's main drag, but caters to grown ups with interesting pies and a nice wine list. Harlow's is a greasy spoon and college hang-out, but the chorizo and eggs might be worth it.
House of Tricks
114 E 7th St, Tempe, AZ 85281
1021 W University Dr, Tempe, AZ 85281
603 W University Dr, Tempe, AZ 85281
La Bocca Pizzeria
699 S Mill Ave, Tempe, AZ 85281
This recent thread has a lot of options for downtown Tempe, mostly inexpensive and very casual: http://chowhound.chow.com/topics/642449 (it's called "Dining options from PHX hotel" if that link doesn't work). A couple of miles farther south in Tempe, I really like Kabab Palace (Afghan) and Classic Italian Pizza (dinner only, and a little tough to find, tucked into the far NE corner of a strip mall); both of these are also pretty casual.
If you're looking for a gourmet meal and money is no object, Kai is fantastic! Quiessence is also very good for a high-end meal not far from Tempe.
Classic Italian Pizza
1054 E Baseline Rd, Tempe, AZ 85283
5594 W. Wildhorse Pass Blvd, Chandler, AZ 85226
Quiessence Restaurant & Wine
6106 S 32nd St, Phoenix, AZ 85042
710 W Elliot Rd, Tempe, AZ
In Tempe, Four Peaks Brewery has good beer and quite good bar food-- pizza, sandwiches, etc. It's definitely a college place in the evenings (mostly grad students) and gets quite crowded, but in a very laid-back way. They also have a good Sunday brunch. Papago Brewery is not far from Tempe, and has the best beer selection around (but much less tasty food). Sometimes it's pretty calm, but it can get quite loud and crowded when certain sporting events are on (I've never quite figured out which ones). Although they're beer-centric, neither of these places is big with the barely-21 crowd (most of whom will be headed for cheaper beer).
post was for Phoenix, and area-tempe; so I thought these would be within the parameters.
For bars, I used to like to hang out at the bar at Sanctuary-Elements, very nice-great wine list and half bottle list.
I am not sure of many in Tempe area, most are college hang outs, which are fun, but not sure what you are looking for.
Check out NOCA, 32nd st and camelback, great food, great winelist. On paradise village parkway, check out Yasu Sushi Bistro. It has a small sushi menu, but specializes in Japanese Sumibiyaki, great food! It doesn't look like it from the strip mall it is in, but fantastic food!