I've spent a lot of time in Marathon since my in-laws have a place there. The Best Places to Stay are Tranquility Bay, Holiday Inn Express, Sombrero Reef Inn, Sea Cove, Banana Bay, and Bonefish Towers. I know that middle area of the keys the best. Its central location makes Marathon the perfect base camp to the entire string of islands. You will love the food at Sunset Grille, Keys Fisheries, Curly's Coffee, Sweet Savannah's, and the Tarpon Creek Grill. It's less than an hour drive to either Key West or Key Largo. Here are The Highlights of the favorite attractions for kids in the area: Seven Mile Park, Coco Plum Beach, Pigeon Key Park, Crane Point, and Sombrero Park Playground. You can view an area guide for more ideas.
Once you get all the way down to mile marker zero the activities are endless. We like to save and the Spindrift is one of the best budget hotels on the key island. When you're searching for your rooms on travelocity, I would definitely sort by the lowest price to the most expensive price. It is really important to understand what you can get at the lower price points. Once you know that the baseline for a room is this particular price, it makes it a lot easier to know if you're making a good decision on a medium price place or even a deluxe type accommodation. It also matters quite a bit the length of your stay. For one, two, or three night stay overs, I would lean towards the cheaper units in general. You are going to be so busy during these three days, that there will be very limited opportunity to take advantage of your hotel facilities. You might use the swimming pool quite a bit, but that's all you're going to do because you're busy out and about enjoying this wonderful island. When you're staying for a week or longer, everything is different and you need the very best thing that was in your budget range.