Ahh, never mind -a little bit more focused Googling and I have answered most of my own questions. Any personal experiences still welcome, of course!

It was free to do this a couple of years ago. You can just have lunch on site and walk through the dig. You're not allowed to use the pools unless you pay for a day pass though so I wouldn't try this if your little girl is tempted by the pools!
The beach at Atlantis is lovely so your mom might want to spend some time there or the zoo in Nassau is a great place to spend a couple of hours.. you can feed the birds (lorikeets I think,) watch a flamingo show, and the grounds are filled with tropical plants and flowers including orchids. It's very pretty and has plenty of shady spots if you need to get out of the sun.

Here's a link
http://www.ardastra.com/

Thanks - the zoo was my other thought. DD's not going to care about the pools and my mom isn't going to be comfortable taking her near the water alone anyway. Glad to hear about the shade -I'm always a little paranoid about that!

We have seen staff stop people wihtout an Atlantis wrist band at the Dig and the Aquariums.

Here's another thought. If you're coming in on a cruise, can you make arrangements to leave your daughter in the kids club while you visit Nassau? Then both you and mom can relax while daughter plays with friends she's made on ship and can take a nap when appropriate instead of when you're on the beach or at the zoo. You'd probably need a stroller for her all day on land.

Check the time you arrive in Nassau. The Dig admission was free after 6 pm (you'll have to check if that is still the case).

When we went to Nassau (land vacation, not cruise) it was $25 p/p to view the aquarium and digs. I believe the price is higher now. Check their web-site. We much preferred the Ardasta Zoo and Gardens over the Atlantis. If you can, go when they have the marching flamingo show.

I've already checked the Atlantis website, the price is up to $35 per adult. I am going to leave the Atlantis vs. Zoo decision to my mom, as she'll be the one making the outing. Thanks for your suggestions, GBelle, but we don't live near my mom, and she's accompanying me on this cruise primarily to look after DD, so Grandma time will be highly prized! We will, of course, work around her nap time and she'll be in her stroller. KVR - the marching flamigo show looks great! Will have to make sure I jot those show times down!

Definitely go early for the flamingo show and sit near the front (again there's plenty of shade). They allow for lots of photos with the performing flamingos at the end. My kids were told to stand on one leg and were flanked by copy cat flamingos!

Wow leaving the kids on the ship isn't something I'd do. Also, my husband and I just visited Nassau on a cruise. I haven't read throught the results above, so forgive me if I repeat something that's already been said:

They charged us $40.00 each for the Aquarium visit. We had a bracelet. They informed us that we would not be permitted to walk through the water park or on the beach. When we returned I emailed the Atlantis myself. I asked them if there was a way to NOT be a hotel guest and yet still spend the day using all their facilities...

Yes you can! It will cost $120.00 per person for use of all facilities all day... one day only. NO food included. I think that's a deal my husband and I will look into on our next cruise, since the ship docks all day long. It's only worth it if you want to see Atlantis that badly...

The ship's tour to Atlantis: I heard it was awful. We didn't do it because I am semi handicapped and cannot walk fast. They were rushed through the tour and then left to fend for themselves. They were all sorry they paid for this and wished they had taken a cab like we did and did things on their own.

Once you get to the casino in Atlantis, there is a window to pay for the passes you wish to purchase. I must say this...

HANDICAP BEWARE! There are stairs to climb. I was able to do this, but not everyone who is handicap will... lots of stairs and lots of walking.

You can also rent a wheelchair or a motorized scooter for the day. It is the same price as what Busch Gardens would charge...something like $48.00 for the scooter. Sits ONE person only...like the Jazzy chair on TV. They use an outside vendor who I read will deliver the chair to your room. So if you are't staying there, I guess they will deliver it to the casino...hopefully so.

Atlantis is gorgeous!!!!!!!!!!!!!!! It's very expensive and if I did return as a guest, I would definitely stay at Comfort Suites across the street and save tons of money, since they give you full rights to the all the facilities on Atlantis

You may also want to look into getting a room at the Comfort Suites across the street from Atlants. You don't have to use the room, but guests there get FULL use of all Atlantis facilities. Depending on the size of your party it could cost far less that that $120 all access pass per person.

Yes it is cheaper as I stated...but this person wants to take the tour while on a cruise.

Actually booking a room at the Comfort Suites is very common for people ON a cruise. You get essentially a day pass to Atlantis and a place to shower afterwards if you aren't going back to the ship after Atlantis or an afternoon nap if you have little ones. We looked at this last month and the room at the Comfort Suites was like $250, so a deal if you are a family of 3 or more.