If you are coming from the Maryland side on any day that there is an event in Old Town, I suggest taking the Potomac Water Taxi. It's a little pricey (and the same price for kids as it is adults, which I've seen a lot of disgruntled parents), but not having to drive over the Woodrow Wilson Bridge or attempt to find parking in Old Town is totally worth it. We used it as an excuse to get our cast of "Ferryboat" on a ferryboat, which was something we had arranged back in November but then got rained out. Even as a local you pass under the Woodrow Wilson, which is a whole new experience and something that should be done once (especially if you are one of the thousands who have sat on that bridge for countless hours in traffic).Considering the last parade I went to was the PTown Carnival, this one was downright tame. There is also very little variation from year to year (we went in 2006 and I swear it was literally the same parade, plus a Stormtrooper or two), but if you're looking for something to do or are in town, it's worth it!
We wrapped up the afternoon with dinner at the Public House at the National Harbor, and I have yet to have a meal at any restaurant over there that wasn't wonderful. I plan on spending a lot of time there this spring/summer!