We LOVE Downtown Disney! It is a much more relaxed pace than the theme parks, yet can be every bit as fun. I'd have different tips if I knew the age of your children, if you have any.
For adults there are a lot of neat interesting shops, though most are too expensive to really get something really nice. But even the World of disney is amazing, though filled with typical disney items. Lots of neat places to eat - lots of neat photo opportunities. It's absolutely beautiful at night with thousands of little twinkling lights as you walk along the water and duck into some shops.
For teens, there's the typical World of
Disney store, but my daughter likes the store that sells beach and sunwear with famous brands for teens and young adults. She also likes the to play at the toy store with the hundreds of pieces for Mr. and Mrs. Potatoe head. And of course, she loves to eat. Of all age groups I'd say it is most boring for teens, though it holds their attention for two hours at most. She really misses the Virgin store! She could stay hours in their listening to music!
For younger children (3-12) there is a ton of fun stuff. There is
lego land - where there are huge displays made entirely of legos, there is the toy store with pieces for mr. and mrs. potatoe head (a GREAT deal as a suvenir - just buy the actual Mr. and Mrs. potatoe head ahead of time at a discount store). You can buy a box and all the pieces you can fit into it for reasonable price. It's fun picking out pieces and seeing how many you can fit into a box. The world of disney is an attraction in and of itself - HOWEVER, you will be bombarded with "I want this, and this, and this," It's overwhelming even for an adult. To be honest, at times I have felt almost disgusted at all the spoiled and whiney children I see there, and think about all the money that is spent on junky stuff. I prefer one nice souvenir, like a pair of earrings, or a charm bracelet.
For older girls (10-15), the charm braceletes, where you can purchase individual charms at various resorts, stores, etc. and add them to the bracelet is a great nice keepsake!
Of course, there is the Fairy Godmothers who can make your daughter over into a princess at the world of disney, though it can be pricey. We have found if you go and ask, they will let you purchase a crown and just do a little make up and/or sprinkle pixie dust over your little princess for fairly inexpensive if they are not busy. ALSO, one time I did it as an adult - it was fun, but pricey.
Anyway, we really like Downtown Disney for a great relaxing, alternative to a park! It's the great way to spend a nice quiet even romantic evening. Don't miss the Christmas store, and the Art of Disney store!