Just wondering for those of you who use different cassettes for flat rides and super hilly rides...

I have a 39/53 in the front and 11-23 in the back. I'm going to do some insane climbs this weekend and was told I should switch to either 12-25 or 12-27....

Do you guys have separate rear wheels with the cassettes permanently attached and just swap out the rear wheel or do you guys just switch out the cassettes on the same wheel?

I'm not very technically gifted, so I don't really know what it takes to swap out a cassette, but was thinking that getting my LBS to just setup a brand new wheel would be the easiest.