Will be in Phoenix for 1 day (no car, staying in downtown Phoenix, so will have to use public transportation.) I want to spend an afternoon walking around, do a little shopping, see some cute shops, grab a cafe, that sort of thing. Where's the best place for me to go: downtown Scottsdale, Phoenix, other? Thanks!

I'd recommend Biltmore Fashion Park. It has a good variety of shops & restaurants and is outdoors so you can enjoy the weather. It is also more accessible for you from DT PHX since you are going to rely on public trans (Which in PHX means the bus). It would be quite a long ride to DT Scottsdale or Kierland (Or an expensive cab ride). I don't use the bus, but you should be able to reach Biltmore in 1/2 an hour or so with one transfer. Take the 7th st line N to Camelback & get off. Transfer to the Camelback line going E. Get off @ 24th St for the Biltmore. If you want to visit other areas I'd really recommend renting a car for the day as the rental fee would be far less than cab fare to and from Scottsdale. Have fun.

Just came back from AZ. We went to Oldtown Scottsdale. There were lots of interesting shops and restaurants. If you prefer high-end stores, Scottsdale Fashion Square is a great place to go. This mall is huge with high-end stores like Tiffany's and Neiman Marcus. Happy shopping!

I'll agree with bonesaz. Biltmore Fashion Park is the best overall one stop destination for the visitor with no car because it's more unique in its design (outdoor 'mall'), pretty setting, combination of shops and restaurants, and it's not generic feeling. The Fashion Square Mall has all the same mundane mall stores every big city has, plus a few nicer ones as noted above. It was renovated a few years ago and is a pleasant place to shop, but it's still just a big, unmemorable mall.

If you had asked where you could do the MOST shopping in one stop, I'd have said Fashion Square. But you sound like you're after the 'whole experience' of relaxing for a day in a nice environment, shop a little, graze a little, etc. That's more Biltmore IMO.
Kierland would be a good alternative but is a heck of a cab ride from downtown. It would be cheaper to rent a car for a day than cab out there.

Downtown Scottsdale has some interesting shops and restaurants too, but is much more spread out and inconvenient.

Ditto the Biltmore.