pictures of people eating generally turn out HORRIBLE. mouths wide open ready to stuff in another piece of cake

True... but i really menat was people at the table... naturally i'll wait for a break between plates...
I would get a longish lens that is fast (like 2.

if you can and shoot people during the break while they are visiting with others... shoot close up 'portraits' of as many people as you can get. Often people have nice natural smiles while visiting.
-and watch out especially when people greet eachother. they often give a nice big smile then.
Let's see if my 100-400 will do.. it's a bit slow for this... but has much quality, and the camera is also noise friendly, so i can crank up the iso a bit... The greetings is a very nice idea... but guess for those i won't be stealth... at that time i'll probably also need the short lens...
What about funny images, pretty extreme like: Wide angle lens stuck into a face of eating person, focus on front teeth?
I guess this would be a bit radical... probably something less extreme will do... of course one can always try and see if they like it in the end...
As for sense of humour, they certainly have it... i just don't think their idea is that radical... they just don't want to pose a lot (if you ask me, there will be at least some people that will force them to take a pic together, and when one goes, everybody follows, but for that i'm ready...) and want a reportage approach. My problem is that the venue is rather limited and we don't have all those bride's house/groom/arrival/church/drive/arrival/time out for a few pics alone/etc, etc... I'm trying to squeeze some stuff wherever i can juts to add some variation...
Right now i just had a good idea... near the restaurant there is a very fashionable outdoor bar... i'll try to go there with them for a few minutes just to get some "catalog pics" (hopefully).
how about a limited time "special area" where you've set up a backdrop and invite guests to get a photo with their mate/date/auntie?
As said, this may happen anyway... i'm not sure whether i can set up any area, because according to the restaurant set up there is not much space available... Nevertheless the restaurant has a cool feature, a big window (in fact one wall is entirely glass) with a fairly nice landscape... i may just try that.
Details, details details. good luck.
This is also my idela... lots of details... hopefully there will be many...
Thanks for everybody's input and best wishes... it's great to have such a community...
Regards
Francisco Leitão