Wailea is the luxury destination in all of the islands, not just Maui. While I like Ka'anapali, the real estate is almost triple the value in Wailea.. It's your honeymoon, I would go Wailea.^
My wife and I being Platinum Members at Fairmont, we have only good things to say about the Kea Lani.. you're right, the renovation sale beginning at $199 per night is a once in a lifetime deal.. just plan to go to the beach if you end up going Sept. However, if you can swing October, I heard that Kea Lani will have the adult pool and the lower pool open (so just the upper pool undergoing renos).. so you get the discount and the use of the two main pools.. the upper pool is little and the one water slide they've got isn't worth the extra $300 per night that they regularly charge. all suites are at least 840 sq ft.^
Add brekkie package at Kea Lani for $50 per day.. better yet, if you are AMEX Platinum or book through
www.perfectescapes.com, you maybe able to get reno special and free brekkie/upgrade/late checkout.
Want to spend $600+ for a 500 sq ft to 650 sq ft room, go Grand Wailea and Four Seasons. I'm a budget freak.. I'd go renovation sale, and visit the other properties during the day.