If DH and I go to a wedding we usually give $200.00. If it's someone who is very close like a relative we'll give more. If we can't attend and it's not a relative or very close friend I'll give $100.00.
Both my son & daughter have gone to a LOT of weddings since graduating from college. As a matter of fact my DD and her boyfriend flew out to San Francisco from the east coast yesterday for a wedding this weekend. They will be making a small vacation out of it. Now I'm curious as to how much they will be giving (will have to ask when I can) since airfare & hotel are not cheap!
My son who is single usually gives $100.00 but as a guy (showers still tend to be women only) doens't spend on a shower gift. I think your daughter should give what she wants....$100.00 is fine. However you never mentioned what she spent on a shower gift. I would not have bothered with one if I weren't going to the shower & wasn't close to the person since a wedding gift would have been sufficient in my opinion.
Just because she's invited to a destination bachelortte party doesn't mean she must go! ...of course if she wants to & has the funds then that's different.