We will be staying in Riquewihr for a week in early summer, and I had Strasbourg planned as a day trip.

The more I look at it, the more I wonder if we should try to stay there 2 nights?

We will have a car, is it difficult to drive in Strasbourg?

We were there in Oct., and I was surprised at how much traffic there was in Strasbourg. I'd do the Strasbourg piece of the trip at either the end or beginning of your stay in Alsace as you will not need a car in the city itself.

Unfortunately that won't work, I already have some reservations made, we would need to go to Strasbourg in the middle of our trip.

grandmere, how many days did you spend there?

You aren't even allowed to drive in parts of central Strasbourg, so if you drive, you'll have to find some place on the outskirts to keep the car.

I spent about 3 days there, I guess, a couple days would be fine. But I think a day trip would not be terrible, actually, just depends how many of the attractions you want to see. You could see the cathedral and that museum nearby, and walk around a bit. I liked the Alsatian museum and the one in Rohan palace.

My husband loved that museum, Christina! It was right across from our hotel, and he spent an hour or two there while I was zonked out w/a serious case of jet lag, but he raved about that museum. The sections showcasing archeology back many thousands of years captivated him.

Another possibility might be to take a train (I would prefer a train over a bus) from somewhere near Riquewihr? Anyone know from what town we might be able to do that?

We did it as a day trip last Sept. which was ok for me since I had been before, but I think my wife would have liked to stay longer.

Unless it has been recently removed, there is a large underground parking garage near Place Gutenberg, about two or three blocks from the Cathedral. A bit expensive perhaps, but that puts you right in the city center. We parked there for a few hours to re-visit the city center and have lunch when we were driving from Frankfurt to Basel.

Find a hotel with parking, and stay at least on night.

That sounds like a good idea for the OP, heti. Our hotel, The Rohan, was in the pedestrian district, but they did offer parking off-site to guests w/cars.