Why not mix Rum, pineapple juice and orange juice (and some sugar to tatse) together with lots of ice cubes- the good thing is even if you buy the cheapest ingriedients, for example own-brands, it will still taste good. Adding lime and orange wedges will always make it look and taste even better :-)
I'd add to joninfrances recipe - the best rum punch I've ever had was a bottle of bacardi (white rum), a bottle of rum, about half a bag of sugar and two cartons of fruit juice.
I made a punch for a barbecue/party a couple of summers ago. I think it had vodka, a rose wine, orange juice, chopped apples and oranges. It was stood in the freezer for an hour or so til it was wanted. I was flat on my back, passed out by 9pm!! ( I had 3 glasses!)
Never doing that one again! lol Went down well with everyone else who had the common sense to stick with just a glass or two!