For a trip planned around organized day tours, I think you've done a great job! I don't know the specific hotels or tours you mention, but thought I'd mention a few things you might want to consider:

I thought both Coba and Punta Laguna are more-or-less between Valladolid and Tulum, so visiting en route (if possible) might make most sense.

Chichen Itza is nearer to Valladolid than Merida and can be seen easily on one's own by taking a bus from Valladolid (rather than taking a tour).

There are some stunning cenotes just outside of Valladolid in Dzitnup that can be seen on one's own and without a car in a half-day or less.

Does your time in Merida include a Friday night, Saturday (day and night), or Sunday day? There are some wonderful public events suring this time - markets and folk dance performances and so forth. If you have any interest and can be in Merida during this times, you might find it fun. I sure did!

> Merida, afternoon in town incl. museums -- Do NOT miss the archeological museum in Merida! It's small, but I thought the collection exceptional.

BTW, if seeing flamingos is important to you, I think they don't usually go to Rio Lagartos until April or so - I think they winter at Celestun. Not at all sure, though! Also, if you are still playing around with schedules and options, I thought the bird watching tour in Sian Ka'an (south of Tulum) quite good. That tour also included a dip in a cenote, guided walk through a mango grove, etc. But its' been a while since I was there (2008?), so it could be quite different now.

Hope this helps!

If you're wildlife enthusiasts, I would strongly recommend that you try to visit Sian Kaan Biosphere.

I would base myself near Tulum for that, and also tour Coba from that location (MUCH closer to Tulum than Valladolid). I would also recommend renting a car for a couple of days--it's really convenient, the roads are pretty good, and it'll save you money.

We did a similar 2 weeks in 2010: Tulúm, Valladolid, San Felipe (on the gulf coast for tarpon fishing and flamingos), and Isla Mujeres; I visited Mérida after my husband flew home and then spent 2 weeks in Chiapas and a week in Guatemala before flying home. You can see our photos with blog and travelogue links here:
http://www.flickr.com/photos/staceyholeman/collections

In general your plan is good but as much as I love Maya sites, I think I'd leave Merida and those sites out if it was my trip. It seems like too much gogogo and not enough time to enjoy the culture and ambiance of the places you're planning to stay. Just my 2 pesos' worth, have a great trip, whatever you decide!

Thanks everyone for your really helpful replies.

I agree that there's some backtracking and illogical routes, but I just can't find tours that do what we need them to from each place e.g. a tour taking in Coba and Punta Laguna with a drop-off in Valladolid. We'll definitely try to find time for Dzitnup and Sian Ka'an, visit Coba from Tulum (which is doable by tours), and make sure to be in Merida on a weekend, though - thanks so much to you all for those suggestions. And hopefulist, I think you're right that it may be a bit packed - I'll look at it again and try to give us some more breathing space.

I'm hoping to finalise the itinerary this weekend, so any other feedback would be much appreciated. Many thanks again.