It can be pretty comical (and impressive) to see what kind of clothes you can get at a thrift store for $5. Pick out outfits for each other (or for yourself) using no more than a pre-set budget ($5 is plenty), then wear the outfits to do one of the other date ideas (bowling, ice skating, etc)
Really old people love it if you come to visit them or to sing to them. They are full of amazing stories, and if they’re old enough, they won’t really care who you are or why you’re there they are just happy to see you! It will make you feel good, and give you lots to talk about.
Missionaries are always looking for help to do service, find people to teach or assitance with any of their volunteer activities. Get in touch with some and offer to help them — it’s very rewarding, and you can see what kind of person your date is!
LDS temples, cathedrals and other impressive buildings can make for a great place to walk around or to sit and talk (at night, they are often very well lit). It’s great for having conversation and talking about things that really matter.
This is another thing that you can do MUCH better now that you’re older. In High School, we’d toiletpaper our teachers houses and people we didn’t like. But it’s a good trick even for people you do like.
Most places don’t care as long as you’re quiet. It’s pretty easy to stroll in and park as if you are checking in and then sneaking back to the pool area. Have your swimsuit on under your clothes, then just strip down and hop in! Many “ritzy” resort style hotels have some really sweet pools.
Camping is a blast with friends. Be sure you’ve got all the gear you need, and bring along card games, board games, snacks and lots of wood for building a giant bonfire. If you don’t want to camp overnight, grab a campsite (or if you’re in arizona, the desert works fine!) and build a giant fire for a few hours.
Lots of places have christmas lights in December. If you don’t want to drive around and look at them, consider paying to go to a zoo and see the lights. They’re often very well done, and have extra goodies like apple cider, music and entertainment!
Not quite as much fun, but still doable without a telescope. Make sure you go a LONG ways out of town so that you don’t get the light pollution. When you’re under the stars on a clear night in a remote place, it’s truly breathtaking.
Particularly true at small airports, you can get up close to some really cool planes. You can also sit on the car hood or on the back of a truck and watch the planes take off and land. Very romantic, good chance to talk (also good to combine with another activity like card games)