In my circle, we're all in our late 30's to early 50's, most hovering at 38-40. We have a problem (I was literally just talking about this yesterday with a friend while discussing plans for a Memorial Day party) - those of us that host, and there's really only a handful of us, have an over abundance of liquor. Good liquor. And usually at parties tons of beer. And very few sodas and mixers.
This happens because the folks who don't host (small apartments, intimidated of hosting, etc) tend to over compensate by always bringing a big bottle of premium liquor or a case of beer. And then leaving it. And this cycle has been going on for years. Sure everyone drinks some. And they encourage others to drink some. But we're not 20 anymore - we can't even as a group of 25 people drink 3 bottles of Jack Daniels, 2 bottles of Sky, a magnum of Cap't Morgans and a quart of Johnny Black, along with 3 cases of beer... plus the 20 assorted bottles left over from the previous parties.
So in my circle, bringing mixers is very much welcome and would not be seen as cheap in the least. Especially something novel or fancy - a big bunch of mint, some simple syrup and several limes - YUM mojitos! Blood orange juice - oooh fancy screwdrivers! Pomegrante juice and lime syrup, coconut milk and pineapple juice, etc.
I once brought a jug of pre-mixed banana juice, tangerine juice and strawberry-banana V8 Splash, and a jar of maraschino cherries - people loved it. They mixed it with vodka, they mixed it with rum, they mixed it with gin, and some people jut drank it with ice and no alcohol; it was fruity and unexpected and ridiculously easy. I literally bought a quart of Looza banana juice and a 16 ounce of each the V8 and the tangerine, and just poured them all together into a half gallon pitcher. Cost less then $10, took less then 2 minutes, and was a huge hit.