I made a very similar trip last year... Almost the exact same thing you're doing except I only skied 2 days.
We were able to get Very cheap tickets to Loveland and did that for one day ($30 per person) and then got BOGO tickets to Copper for $60.
So those 4 days passes to Copper would be cheaper per day than trying to get into several places. IMO copper is plenty large to ski for 4 days (for me anyway).
We had 3 guys so we rented a condo in Dillon for $130 per night ($90 per guy) which was a really good deal compared to what else we found.