Cadillac Ranch is always a good time! I love the location at Tempe Marketplace and think they have a superior patio (my only complaint is all the smoke-- but that's not their fault).
Parking is free, it's easy to get to, the space is large so it's never too crowded (even when there are a ton of people there), drink and food selection is great and I love the decor! Where else can you sit under the cover of Rolling Stone magazine from the 80s with Jon Bon Jovi on it?
This is a great place for lunch and the portions are just above medium size. Dinner is great too- just don't go for a late meal as you'll be trying to eat as the beautiful people who are looking to party show up and the DJ turns up the volume. I love the AZ Mac N Cheese- try it!
At night, this is one of the places to be seen in Tempe. CR turns into a great nightclub with great music and atmosphere! There's not a bad looking bartender in the lot either. I miss the mechanical bull because it was always a treat to watch drunk people try to stay on 8 seconds, but I get that it was probably a liability!
Finally, this is a great place for happy hour and groups. I have met here with my sorority alumni group on occasion and they've always been really accommodating!