Activity for Erin

So FH and I are planning to invite 100 guests to our wedding. Our venue can accommodate up to 150. I'm wondering if we decide to invite more than 100 what are the areas where costs will go up-besides the obvious like food, drinks and wedding favors? ...

Any creative people wanna help out with a cute wedding hashtag? My fiances last name is Nussbaum so I'd like to do something with that. Our first names are Erin and Andrew (Drew). Thanks in advance!