I have a few questions that I haven't seen answered so I thought I'd post them all in one thread. Please keep in mind we are very much budget travelers.
Mrs. DennyO and I are going to France for the very first time. We arrive at CDG at 0730. I figure we'll get into Paris about 0930 (realistic?) and most hotel check-ins are 1400. Naturally, we'd like to do something in between but will probably be somewhat tired. Whatever we do, we don't want to be hauling around our luggage for 4-5 hours. If we go straight to the hotel, could we leave the bags until check-in? How about taking the RER into town; are there lockers available?
[I]
9:30 sounds realistic by cab, maybe a bit longer by RER since you need to wait for the next train, etc. Depending on where your hotel is, the RER can be very convenient, if not take a cab. The RER ticket machines at CDG DO take non-French credit cards. If money is truly an issue you can take the RER into Gare du Nord and then a cab from there, but by that point you really aren't saving much if you have two people. If you do go the RER route, I'd recommend buying your return tickets (if needed) at the same time, they don't "go bad" and it can be difficult to find a machine that takes credit cards or an open window without a long line in central Paris, better to just buy them all in a single transaction.
I know of no left luggage in the RER, but I'd just go to the hotel and drop the bags. They will certainly hold them for you, and you may find that a room is actualy available for you immediately. Not specifically RER, but I believe there is left luggage at Gare du Nord.[/I]
The Segway tours look like fun and a good way to get oriented to the city (although expensive). Has anyone here done them? Would we be too tired to enjoy them, i.e. should we take a tour bus?
Haven't done the Segway, but if you want a relaxing intro to Paris I'd to the river cruise thing. It seems sort of trite, but you do get a good overview of things and the views are great.
Our plan is to spend the first day in Paris, then two in Rouen/Giverny, then two in Burgundy/Dijon, then four in Paris. I have seen some disparaging comments about Dijon here, but I was looking forward to visiting (and sampling) some wineries. Are there alternatives you would suggest?
Haven't been to Dijon. For a taste of something different we like Strasbourg, which with the high-speed train in place is now a much faster journey.
The trip by train for two (2d class) works out to almost the same cost as renting a car. Advantages to train: don't have to drive, can't get lost, and it seems more "authentically" European. Advantages to car: flexibility on when to leave and where to stay (I saw a nice-looking B&B outside Dijon), and freedom to stop at any small town that suits our fancy as we travel. Am I missing anything?
My only advise is that if you want a car you might want to pick a rental place that is easy to get to my metro but on the outskirts of Paris in the direction you're traveling. I wouldn't want to negotiate Paris itself by car.
By the way, my reading of French is passable, I think I can speak it OK but I have concerns about oral comprehension. A major goal of mine is to improve my French.
You'll be fine. A useful phrase to learn is "Pardon me, but I'm a stupid American (or whatever) and don't speak much French, can you help me." 
Finally, we enjoy taking pictures with our camera and can think of no better place to do so. Does going around Paris with a camera around the neck mark us too much as tourists, an invitation to pickpockets? Do many people go around town with backpacks?
On my last trip I carried a messenger bag which held the camera, a smallish guidebook, gloves and hat (it was cold) and maps with ease. It was also handy for holding all those chocolates and rotisserie chickens we bought (see previous thread) and I never felt out of place.
Thanks
And thanks to Flyer talk: our plane tickets were "purchased" with miles. ^