Uni is obviously fun!
We go through the 3 basic ones, missionary, cowgirl and doggy most times we have sex. The first is good for slow starts with lots of kissing and the other two are our faves, hers cowgirl and his doggy. That's not to say we don't both like all of them. Usually we include other ones, her lying face down and him on top is a regular position. Quickies are often done standing doggy style.
If we're playing with another couple we often do some of the group positions like M on back and two F on top, one on pussy and one on face, or MFM DP. When younger we used to do the more playful ones such as wheelbarrow and M standing and holding F, but we're not really built for those now!
You can get an IPAD app called "Sex Life Positions" with positions grouped in 9 categories and sub-divided, for example it shows 13 different group positions. It allows you to mark the ones you've tried, rate them and highlight and the ones you like best.