Sorry to hear about your wife's cancer- dad went through it - stay tough!

My idea:A 2 day thing over a weekend

Day 1 - Family day! - have a (pseudo) suprise birthday party for her - you do it all - cook-clean-invite friends and family and have a day just for her to visit and laugh with her friends and family.... (serve (potent) margaritas! - if that is your thing)
Day 2: Movie day: Rent a bunch of movies the next day and decompress with her - just the two of you (and kids if you like) - pop popcorn - cuddle - enjoy each other - top it off with a bowl of baskin robbins world class chocolate ice cream - a massage for her - then... (really if you do this right... she falls asleep in your arms and then... take a moment for youself and thank God for the blessing she is to you).
Make sure to kiss her and tell her how much you appreciate her and all her efforts to make you marriage/life/etc work.
Again - remember how lucky you feel to have her in your life and imagine what you would be without her...
It sucks - (I only know my situation - not yours...)
Cherish the moments you have and hope for more.
Pop fought for 7 years - what a trooper - we were so proud. But he had something incurable - from Vietnam and the Agent Orange...
Your buddies here at Colo AR-15 are here for you - friend.
Don't forget that... we are here for you... "should you need us".