23, looking for thoughts on my two card “portfolio” and future plans

I'm 23 and have been very fortunate with my career so I am trying very hard to maximize every dollar I make from a young age. I've already established a good retirement/investment and general budgeting plan, however I'm looking specifically for thoughts on my credit cards now.

My first card was an Amex Gold because my partner and I plan to travel a lot in the next couple years. Recently, I've just opened a Capital One Quicksilver after being denied a WF ActiveCash for having too short of a credit history (I figured I was being ambitious applying for it 6 months after opening the Gold). Between the 4x points my Gold provides on dining and grocery, and the 1.5% cash back the QuickSilver provides on everything else, I feel like I've managed to cover all forms of shopping/spending with the highest rewards available to me at the moment.

Since I'm young with very little credit history and have some student loans my credit score is not where I'd love to it be (Fico 690). In 12 months from now I'm hoping to be around 715-720 by continuing to shrink my student loans, under utilize my QuickSilver card ($20,000 limit, expecting to have at most a ~$1,200 bill per month). If I get to that score, I think I will try again for the WF Active Cash as I will have about 1.5 years of credit history by then (all on time payments and under utilization), my mix of credit will be better, and I'll have less student loans.

My questions: Is it crazy to apply for the Active Cash card a year after being declined? If I were to get the Active Cash card should I cancel my QuickerSilver or will that hurt me? And generally speaking, how many credit cards does the average "power user" have.