You'll get a million answers for towels, so I'm not going to give you mine. But for wheel wells, the only thing that really holds up is DLux.
It's a LOT of work though - I did it. You have to pull the wheels and get the wheel wells perfectly clean. This is not as easy as it sounds. There will be tar and all kinds of embedded garbage in the plastic. Just when you think it's clean - you'll find more dirt. It takes SEVERAL rounds of clean and rinse to get them clean.
If your going this route, I'd recommend Tuff Shine Tire Cleaner to clean the plastic. You will also likely need some type of solvent type bug and tar remover like TarX.
After its all cleaned - rinse well and wipe them with Eraser. Then apply DLux. You will use a lot.
This is the type of work you do on a show car or a garage queen. I would not waste your time with a daily driver, as it will still get pelted with like a zillion rocks and pieces of dirt on a daily basis.
If your interested, I prolly have pictures of the process somewhere.
For a daily driver, just spray them down with Megs D4510 after each wash. I've tried several "dressings" - and this is the best. It doesn't leave a greasy mess the next time you clean the wheel wells, and it's aerosol - so it dries quickly and spreads evenly.
You won't need an applicator or have to spread gobs of greasy solvent based dressing (common products sold for undercarriage) - that will leave a greasy mess and turn into brown sludge the next time you clean the wheel well.