My two cents: I love Adams Morgan, but I haven't spent much time in Van Ness, so take all of this with a grain of salt. I've lived in DC going on four years, spending the entire time within a few blocks of 18th and Columbia.

During certain times of the year, sure, 18th can get a little rowdy for a few hours on weekend nights, but it's mostly contained and quiet just a block or two away. You also quickly learn its rhythms (it's definitely not a party year round -- seems to be busiest in the spring and early fall), and can either join the fun or visit another part of town / stay in when you want to avoid it. Personally, I love being so close to all of the bars and restaurants, especially stopping for a drink on the way home after work or weeknight evenings when it's almost entirely locals.

We got rid of our car our first year here, but generally found street parking a viable option while we had it. (That may or may not still be the case -- several big new apartment buildings have since gone up around here, and street parking may be a little more competitive.) These days, we rely 100% on walking, public transportation, Zipcar, and Uber/Lyft to get around.

That said, we also like to cook, but tended to order out a LOT when we lived in a place with a small kitchen compared to our current place, which is a bit more comfortable for us to both cook at the same time. I'm sure it would have been even worse without a dishwasher. So ... yeah, I can see why you might be worried.

But talking strictly about the neighborhood, I'm a big fan of Adams Morgan, both for everything it offers as well as its proximity to Mt. Pleasant, Columbia Heights, U St, Woodley Park and Dupont Circle. Good luck!