I love roasted anything, and sweet potatoes cooked in the roasting juices around a roast meat is the tops.
Anyway, I cook them at a very high heat at the very lowest shelf of the oven, with olive oil, salt and pepper. I would avoid adding anything sweet to them, since they will already brown too easily, being sugary on their own. I use parchment paper so they won;t stick and the nice brown stuff will come away still attached to the potato. I also cut them in long wedges, with a very sharp angle - that is, if you cut them in half lenghthwise, and then cut that half in half lenghthwise, and then cut each quarter in half lenghthwise, you'll get one very acute angle and two wider angles (if you look at the cross section). These corners make for nice crispiness.
I also like to roast them with regular potatoes. Lots of salt and pepper.
I also sometimes just put them on the floor of the oven. They get nice and brown. Use a LOW-sided very wide roasting pan (cookie sheet with a less than 1 inch border). That way no steam develops, and don;t pack them too close. The best results i get if i toss them with oil before putting on the baking sheet (with the parchment paper) so all sides are lightly oiled. Salt and pepper of course. They always come out nice and brown that way, usually at the top temp of my oven.