No credit card required
Browse credit cards from a variety of issuers to see if there's a better card for you.
I doubt anything is going to drastically change in your report in the next week to get a larger CLI. I would take the $100 they are offering and then you will get your credit steps. Mine went from $500 in February to $1500 in May to $2000 in August. I'll be eligible for another CLI in February.
I would also ask if your account is eligible for rewards. This will pretty much make your Platinum a Quicksilver. 1.5% cash back is a good thing to have.