I am sorry if I gave incorrect information on the beaches that allow dogs. I do know that the beaches in Jax (Atlantic,Jacksonville,PonteVedra and Guana River State Park & the public St Johns County beaches allow dogs on leash on the beach.) We have also taken Pup to Big Talbot and Little Talbot Islands.
Here is the list we got when we moved here last year, for Parks that allow dogs:

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Anastasia State Recreation Area
Big Lagoon State Recreation Area
Blackwater River State Park
Blue Spring State Park
Collier-Seminole State Park
Dead Lakes State Recreation Area
Falling Waters State Recreation Area
Florida Caverns State Park
Fort Clinch State Park
Gamble Rogers Memorial State Recreation Area
Gold Head Branch State Park
Highlands Hammock State Park
Hillsborough River State Park
Jonathan Dickinson State Park
Koreshan State Historic Site
Lake Griffin State Park
Little Manatee River State Recreation Area
Little Talbot Island State Park
Manatee Springs State Park
Ochlockonee River State Park
Oscar Scherer State Park
Rainbow Springs State Park
Sebastian Inlet State Recreation Area
St. George Island State Park
Suwannee River State Park
Three Rivers State Recreation Area
Tomoka State Park
Wekiwa Springs State Park

MsMuir, it may not fit the running on the beach/ sandy paws image, but check out the free run dog parks. They are a great alternative. It's been years since I took my labs to swim in the ocean (Jekyll Island, GA) but my current labs love swimming in the pond every day. Most dog parks have a lake or pond for swimming.

Jekyll has dog-friendly hotels as well.

If you don't mind driving to the Panhandle, rent a house in Indian Pass or Cape San Blas. There are no hotels in the area - just rentals. I've been on the beach for a week and see only 1 family or two (from afar) all week. My dogs love running the beach and chasing birds. Never catch anything but they have fun trying!

Yes, this is the dog park that I mentioned where they have their own lake and woods :)

http://www.jaxdogs.com/

Gee, I guess our dog isn't the only one who takes a "get off my beach!!" tack with the waterfowl! (and the waves...!). Anyway, he went with us to Seagrove Beach last year and was one of many pooches enjoying a romp along the shore.

MsMuir, there are a few chain hotel/motels that accept dogs, but most are too far from the beach. We stay at the Comfort Inn on South Forest Beach. It's nothing fancy, but just fine for us and is very reasonable in the off-season. It's across the street from the beach, but you have to turn right and walk about a quarter mile to the closest public beach access (it's a very nicely landscaped walking trail that traverses most of the island). Turning left from the hotel is just as far and takes you down to a busier section of the beach (where there are restaurants and a shopping area).

The beach, depending on the tide will be big or huge, very flat and firm, suitable for running with or chasing your dog.

Scarlett, thanks for that URL to the Dog Park in Jax! That's really amazing!
I didn't know there were any parks like that!

Here in Brevard Co. they do have what they call dog parks, but they're tiny!
No water...well to drink , yes, but no ponds etc. I did fine a kind of nice one in Sanford...about 30 miles away
and we do go there sometimes so Mandy
can socialize with other dogs. Nothing is nearly as nice as this one in Jax. Thaks again.

starrsville, Thanks for all the links!
Will check them all out today.

andy...thank you too. We decided against Naples since we heard it was really crowded, but most of all it sounds like a most dog unfriendly place.

Scarlett...you sure have loads of pages
thanks for taking the time to send them.

tuckerdc, where is Seagrove Beach?

Brian, do you have any idea what the weather is like there in Dec?

I'm off to check out all the info you kind folks took the time to send. Hopefully we can make a decision soon.
Seems like when you pland a trip for the holidays, especially with your pet,
resos can't be any too early!

Thanks again everyone!

If I was a betting man, I'd wager it'd be somewhere in the lower 60s during the day and upper 40s or mid 50s at night. But we've experienced it all from 30s in the morning (that's a cold run on the beach) to 70s in the afternoon (not same trip of course). One crazy Thanksgiving we even took the chairs out to the beach and caught some rays in our swimsuits. Your results may vary.

Thanks, Brian. It doesn't sound too bad...maybe even invigorating!

You should try Key West - they have a great dog beach there right behind a great restaurant by the name of Louie's Backyard. We take our eskie there all of the time. Also, re: the comment from janiekins re: not staying in hotels where pets are allowed - that's better for all of the wonderful people who do have dogs and consider them part of their family. I am sure my dog lives a much better life than you do.

Seagrove Beach is on the Florida panhandle, just east of Seaside.