Hi Carol! This sounds like a lot of fun for your daughters! Since it is the 20th anniversary of the marathon, it's bound to be even more magical than ever.
The great thing about marathon weekend is that ALL Disney Resorts are host resorts and will provide free bus transportation to all race weekend events. (expo/packet pick-up, kids races, 5K, pasta parties, half marathon and marathon)
None of the
Value Resorts are really close to the race areas, but that won't matter. If I were going to choose one, I would base it more on theme preference (do they like movies? sports? music? animation?) and budget. The Art of Animation is the newest Value Resort, but it may be a little pricier. You can call 407-WDW-IRUN to book their resort packages.
All of the Value Resorts also have bus transportation to all of the Disney parks and Downtown Disney...so your girls will have convenient ways to travel, no matter where they want to go!
Please let me know if you have any other questions as you and your girls get ready for their big race!