Jane - if plan is hiring for a month, you are better of BUYING a used bike and selling it when you are done, seriously. Most bike rentals (hirings) are $1000+ per week, MINIMUM and usually more, ($1200) PLUS insurance, (unless you want to charge a damaged bike to your credit card, maybe even a "bond" required). Most rentals are BMW, Harley and Honda, although there may be a Triumph here are there, I haven't seen them.
You may want to buy a bike on eBay on East coast, ride to West and sell on eBay or other means, with auction end to coincide with your arrival for delivery.
You can easily find a used late model, relatively low mileage bike for $4-5000 or even less, and sell for $3-4k minimum, thus you only spent $1-2k for the ride vs. $4-5k hiring. You might even come out close to even given the bike's "story". Get a magazine or TV station to interview you, you might even become famous and bike is profitable! (OK, I'm in marketing, forgive me... but it's happened - internet blogs, etc... have taken hold before).
Echo on schedule, December is possible but RISKY and you'd want to go from Florida straight across to California on I-10 corridor as mentioned (of course, more scenic byways, right? some Route 66 in the western half), but even there can be nasty depending storm and cold front tracks, it's a risky proposition that time of year. You might get lucky, might not.
You would enjoy much more a early Fall track farther North or best, Spring after greening-up has taken hold (April+) across Northeast, Midwest, Rockies (Wyo/Montana) and into N. Cal/Oregon/Wash. You could even follow Minneapolis and famous Minn/Montana "Zen and the Art of Motorcycle Maintenance" book's route for western half, but continue on to Pacific Coast. Or follow the even more famous Lewis and Clark expedition route from St. Louis west, etc... many options. Even better, East/West and return - across North, return South, 2 weeks each way... so many choices!
Keep us up to date on your plans and journey - I'm sure many people would be happy to join you on segments - if you want. Otherwise, enjoy the lone time.
(NorCal) Chuckles
PS - Save some time for PCH (Pacific Coast Highway) on West Coast. Great sections anywhere from Wash/Ore/Calif (switches from scenic to more 4-lane highway some stretches, but overall is incredible - at least 4/6-lane busy sections have Pacific Ocean as view. We're spoiled here and complain about "boring" sections.)
