One or two new cards won't ding your credit much if it is already excellent. Carrying a balance on the 0% card might hit it depending on what it does to your overall utilization. One easy way to avoid that is to use a busiiness card for the 0% balance transfer. Business credit won't report on your personal credit report, other than the initial inquiry. Just report $0 in income and 0 years in business when applying for a business card.

One thing to watch is that balance transfers are often only fee free when you open the account or for short time thereafter. If you are planning on doing a balance transfer every month to pay charges from the previous month you might find they start hitting you with 3% fees. A better strategy is to take a big balance transfer in cash (Citi, Chase, BoA and others have no problem sending you a check). Put it in a savings account to pay for things as you buy them.

The TYN does have a fixed point redemption - 20,000 points for a domestic ticket up to $400, you pay the taxes. There are other threads in this forum with more details.

If you wanted to go with the Thank You Network, I would recommend three cards from Citi.

Purchase card: Citi Amex Platinum - 3 to 5 points on each purchase for first two years, 15K bonus points, no fee first year.

Purchase card 2: Citi Premier Pass Mastercard - extra TY points for flying, no annual fee, 10K bonus. This would be for coverage where Amex is not accepted.

BT Card: Citibusiness Premier Pass: Do the balance transfer with a check to yourself. No fee first year, 15K bonus points.

This would also give you 40K TY points after your first purchase on each card, enough for up two domestic flights up to $400 each.