Ideas on our teenage sons walking down the aisle

I'd just have them walk in the processional. You can ask them whether they'd like to stand up with you at the ceremony or sit down and wait until you need to rings to get up and give them to you. They can walk down in the "ring bearers" spot, I'd say.

If you want to ask them if they'd be comfortable doing a reading or something, you definitely can. Other than that, having them walk in the processional and hold onto the rings is a good way to include them.

They could be your ushers! Or they could just be included in the processional and honored as family members.