On the upside for the Tequila is the fact you can use other Riu hotels facilities in the area, ie bars/lunch during the day and bar/entertainment in a evening.

Although I've never been to the other hotel you mentioned, I'm recommending the Tequila to you. I'm not sure if you've been to a Riu hotel before but they're fantastic and the Tequila's no exception. It's also close to 5th Avenue if you fancy a walk around the shops/bars there and the beach is beautiful.

Only been to the Tequila ( twice) but couldn't find a single thing wrong with it, & there are some great settings for a wedding.

TEQUILA! TEQUILA! TEQUILA! TEQUILA! TEQUILA! TEQUILA!

Oh, and did I mention TEQUILA! :-)

Ok, so I may be a bit biased as I have never been to the Gran Bahia Principe. I've been to the Tequila 3 times now and absolutely loved every minute of it. This is THE best hotel I have ever been to in over 30 years of travelling abroad (and I have been to quite a few). As has already been said, you also have the option of using the Riu Playacar and Riu Yucatan as well.

My advice is to have a look at the Hotel Reviews in the Caribbean section on this site (check other sites as well by Googling "Riu Tequila Review" or "Gran Bahia Principe review") and see which one suits your lifestyle / requirements. (On this site the Tequila comes under Clubhotel Riu Tequila not just Riu Tequila). Also take into account the actual location of the hotels. The Tequila is within walking distance from Playa del Carmen, not sure about the Bahia Principe though.

This area of Mexico is very safe to walk around in

Give me a shout if you have any questions about it

Cheers

Keith

We stayed at the GBP a couple of years ago and booked through the caribbeanwarehouse.
We saved a great deal of money compared to other quotes and whilst there made friends with people on a First Choice package. We had the same rooms, although they had paid to upgrade, and also a better overall experience as our transport was geared to our party size basically giving us a private tour on each excursion.
This year I used them again, but to go to Cuba. We had a "thomas cook holiday" from start to finish but paid a lot less.

You do have to phone them to get a price, but it may be worth it for you as for Mexico, they can book flights and hotel direct and so although you will have to pay the full flight price for your daughter, there may be savings on the hotel accommodation as often the prices are for a room not individuals.
They have a lot of experience over there and can give advice about many of the hotels in the area and as you already know the prices you are prepared to pay, there is no pressure to take up any of their offers.