how can I spice things up?

All you have to do is be there. He's young, he's always in the mood for sex

Just take your clothes off, that will be all the spice he needs. If it isn't you need to get another b/f.

Yes showering together is always a good idea but not so good in a family home if people are home. Don't do it in the shower but a shower can be very intimate and lead to better things. Don't go trying crazy positions that you think you can do because trust me you cannot. Best thing to do is just be there listening to each other, being really open and not being embarrassed to tell each other what you like. It should all come natural and don't worry about how you look so much because this will show, be confident and in the moment. Great sex starts with great communication! You're adults and theres nothing wrong with being open and exploring things together your worst enemy is embarrassment. And honestly, being naked for a whole night is hotter than any lingerie. Being comfortable and confident is very attractive. Playing around together (play wrestling for eg) is fun and intimate and makes it exciting and casual. No pressure makes it better.

Sex is a good way to play and have fun and touch each other. make it a fun occasion, listen to music, give each other a back rub, take a shower together. Add more to the experience.