Our guests loved:
*Cocktails, champagne and (beautiful) canapes on arrival and during photos
*Free bar (for the entire time)
*No wasted time (e.g. while we were having (v quick) photos, we provided a lovely outdoor seated area by a lake with, as mentioned above, food and booze with a quartet playing, we also had a magician which everyone loved)
*A band and a disco and a DECENT dance floor - definitely worth it, people love to let their hair down at the end of a wedding. Don't forget a quieter space for people who want to chat
*A friendly, discrete photographer
*We got married by a lake. We chartered a large boat and took all the guests for a tour of the lake - this was during that often boring, limbo part - after the wedding breakfast but before the reception. We provided booze, played some gorgeous music and everyone LOVED IT! It was the highlight for us (it helped that the weather was lovely)
I have been to a lot of weddings, so I knew not to bother with:
Sweet carts
Photo mirrors, booths
Fancy dress (so contrived!)
Favors - naff