Looking for advice on account combination.

I currently have:

• Cap1 Venture Card - Opened Nov 2015 - CL $16K - Annual Fee $59
• Cap1 Quicksilver (1.5% cashback) - Opened Nov 2015 - CL $4K - No Annual Fee
• AMEX Blue Cash Preferred (6/3/1% cashback) - Opened Nov 2015 - CL $16K - Annual Fee $95
• Discover It Card - Opened June 2016 - CL $9700 - No Annual Fee (currently locked and only used enough to keep open)

I'd like to combine the Cap1 into the Quicksilver to eliminate an annual fee, and because I feel like I get more value from cashback rewards than travel specific rewards. I use my AMEX as my 'everyday' card and it gets a lot of use. I rotate through my other three cards with all of my recurring payments so that they stay open. I request CLIs every six months.

My question is this: is combining these cards the right thing to do? I plan on waiting until after my next CLI request before doing the combination. I know eliminating the annual fee is a good thing, but I feel like I'm overthinking this when I start doubting whether I should combine the Venture into my Quicksilver. I feel like since I opened the three cards at the same time, my average of age of account probably won't be affected too much. Anyway. Some guidance/confirmation/alternative approach is totally welcome!