Easy, most folks prefer cold (if so, there's no re-heating), and keep really well in the fridge both before and after cooking (since it's a root vegetable). Downside is roast time is ridiculously long and you need a lot of foil. I suggest larger beets, without the stalk (produce places call them "loose beets", I get them for $.69 per pound). I make them on weekends, then eat them all week (beet freak, here...).
Roasted beets, my version (folks either love or hate beets, I love them):
1. Wash under faucet.
2. Cut off the top and bottom.
3. Rub olive oil on top and bottom. Wrap in foil.
4. Put on cookie sheet. Bake 350 for 2 hours (yes, not a typo). I make 2 cookie sheets worth, since the roasting time is so long.
5. Remove from oven, loosen foil, let cool for about an hour.
6. Peel (really easy...), then slice (optional) and place in fridge.
I like them cold with balsalmic vinegar, vinigarette dressing, or olive oil and maybe a pinch of salt.