Pork loin is a lot like chicken, in that you can prep it many ways. The more important thing is to not overcook it.
I have used a lot of different preparations. I try to get pork that has not been injected with a saline solution, so if I choose, I can brine it, or do an overnight marinade that has salt in it.
If you like spicy foods, a Jamaican Jerk marinade is good. There are some good recipes on the internets. You can use some Jamaican rice and peas as a side. Recipes for that are also all over the internets. It is very easy to make.
I have also done some cajun spice marinades, and served it with some cajun rice dressing. I have also served it with boudin.
I'm sorry for not posting recipes, but I don't have any to post. I tend to look at recipes for inspiration, and do my own thing.
Oh, there is one other thing I tried that was really good. It is an Italian thing using a lot of rosemary, including poking a hole all the way trough the roast, and shoving some rosemary through the hole. Picture below (sorry, I don't have a recipe). If you look at the top slice in the picture, you can see the hole in the middle. The outside of the roast was covered with a mix of olive oil, and finely diced rosemary and garlic. I cooked mine on a Weber Kettle, indirect heat with some apple wood mixed into the charcoal. So, it was basically smoked, but not low and slow. I had the heat up to about 350, and took the pork out to rest when the meat hit 145F internal temperature.
CD