Rebuilding the Willow Creek Gym--Help!

The gym looks very nice! :) Very nice design of the exterior ! The balconies and porch look great! It is great that there is a sunken pool patio for Sims to enjoy swimming in the pool. Very nice layout and furnishing of the interior. Sims will enjoy using the fitness equipment to keep fit, whilst listening to music through the wall speakers. It is great that there are vending machines to get food and drink from. Very nice blue and white sofas sitting nook for Sims to rest and chat there. The sports themed posters and banner look great on the walls. Sims will enjoy having a relaxing foot or hand massage whilst sitting in the massage chair. The circular floor rugs add a great look to the room area.
It is a very nice gym! :)

I've actually been doing the same thing, improving upon all of Willow Creek and other worlds. I haven't exactly been completely redoing everything, but instead just renovating everything. What I did with the gym is turned into a cafe, which I thought the gym was when I first saw it. For some recommendations, I guess don't make it too symmetrical. I found everything (not just buildings) look a lot better asymmetrical. But still looks great! At least now you have a good base to build upon. Good luck!

Oh, I also really suggest watching a lot of sims speedbuilding on youtube, great inspiration for building projects. Also use real life buildings as a little reference. They help a lot!