I love Scarlett's suggestions, great ideas! One thing I try to do with fruits/veggies is embrace the seasonality. Of course where you live that's a different story due to produce being grown year round.
How about things like melon? Cantaloupe, honeydew, watermelon and other melons are nice because you can slice them in advance (as in, they'll stay good for several days), they're sturdy enough to not bruise in the lunch box and they don't brown.
Grapes are nice and easy, as are grape tomatoes if your kids will eat them.
Pineapple holds up nicely too and canned chunks can be quite good when you don't want the hassle of fresh.
Kiwi slices hold up too if you slice them right that morning and star fruit is OK until lunch time too (both brown if you cut them the night before).
All winter long we tend to go to citrus fruits - they're in season, they're cheap, and kids usually like the easy to peel fruits like clementines, tangerines, cuties, and minneolas. I slice larger oranges into wedges for them and then just stick the wedges in a sandwich bag.
Applesauce counts as a fruit in my house (I live Vermont Organics - all natural, and the unsweetened one is still nice and sweet, not tart). Sometimes we do plain and sometimes I'll get some mixed with peaches or strawberries.
Every now and again we'll do pear or peach cups in juice but they really prefer fresh fruit.