IO should get to $350M.
Vacation is not going to be THAT BIG. It will be more on the level of Tammy (Social Media Buzz is worse than Tammy at this rate, which is even weaker than expected given that it should be doing way better due to the brand).
Keep in mind, it increased on Saturday even with inflated previews. For this type of film, it could have decreased like Bad Teacher and The Ugly Truth.
Other than Vacation & Paper Towns (targeting females with the latter targeting teens due to it being from the creator of TFIOS, which was frontloaded despite fantastic WOM), it doesn't have much competition for the rest of the summer for the targeted audience. Plus, having the same audience percentage as Bridesmaids is a great sign going forward with its legs.
If Bridesmaids can survive against Hangover 2, why can't TW hold well in the 30s for its third weekend. Less than $120M for Trainwreck? Not happening, IMO. 4+ multiplier is a lock if it can drop under 40% next weekend, which is happening for now.
I'm thinking more like $130-150M as its final total but could go higher depending on how it holds during the week and female-oriented films during the summer often have strong weekdays.