I have a similar trip planned towards the beginning of Feb. We bought a 4 of 6 day pass.
I'm curious if I could ride breck during the day, and goto keystone for night session without using my next day. Does anyone know if this is possible?? I'm staying in a ski-in/out at breck, and want to ride as much as I can so I'm willing to drive to keystone for night sessions. As you can see from my location, New Orleans, WE DON'T HAVE ANYTHING TO RIDE AT ALL!!
I'm in Atlanta, which is probably almost as bad as being in NOLA in terms of snowboarding (though I can get a fix by driving 3.5 hours if I don't mind riding down the bunny hill at Cataloochee).
A night session after an all day session is pretty tough. Even if you manage to not collapse and go home early during the night session, you'll end up the worse for it the following day.
IMO, you'll be doing ok if you can stay disciplined enough to wake up, get first chair every morning and stick around till the lifts close each of those 4 days.
Important: If you have never been to Breckenridge, then prepare to have your ass whooped by the altitude difference (ESPECIALLY coming from NOLA).
Take it very easy your first 12-24 hours after you land. Hydrate yourself more than normal. Take it easy on the alcohol (might be better not to booze at all until the 2nd night or so), and if you do ride that first night in, don't push yourself too hard. Even if you don't get headaches or short of breath, you will probably feel off... almost as if you were slightly depressed.
I hope the snow gets better for your trip. I haven't been to Breck in many years, but you can actually get a reasonably priced lunch at Imperial burger, and the the mango/pork burrito at Mi Casa is the yummiest meal I had there.