There is a site that might help you watch the airfares as they go up and down, so you don't have to fret about it; this should all be a fun experience (even the planning) in celebrating a very special occasion.

http://www.yapta.com/how/

I agree with the others that you have lots of time to book flights. As a matter of fact, survey results released the other day found that the best fares (except for holiday travel) are available about six weeks, prior to travel.

If you travel on Frontier from DTW via DEN, you might consider booking Classic Plus, which includes two free checked bags per person, free drinks, STRETCH seating (extra legroom), free DirecTV (on Airbus), and other perks; it is also fully refundable, so, if the fare goes down in cost, you can re-book and get a full refund on the higher fare.

http://www.frontierairlines.com/plan-book/fare-options

If you travel on Southwest and the fare goes down, after booking, they will give you a credit for the fare difference, which must be used, within one year, for future travel. If you don't use it, you lose it, and it's only good for the person named on the reservation.

Please let us know how everything works out.

I also want to welcome you to FlyerTalk and the Frontier forum and hope you have a wonderful time on your special trip.