I have a car to drive during this visit but I am wondering which areas it would still be better to take a Uber or Lyft?

Unless you’re out deep into Northern Virginia (Reston, Chantilly) or Southern MD (Bethesda, BWI, etc) I wouldnt bother with the expense of a car. DC in particular is walkable and very navigable via metro, Lyft/Uber if you don’t want to public transport- parking and traffic will be a pain with a car. Most places in Northern VA and Southern MD are reasonably priced with Lyft/Uber.  

I live downtown and I usually take Uber/Lyft to outcalls in the immediate downtown area or even across the river to Crystal City or Alexandria. The cost of a short round-trip ride within the city is often around the price of parking in a downtown garage, and is usually a lot cheaper than valet parking at the nice hotels in the area.

Best in the country here in DC/Arlington area. I come from a city that has much usage of the services & DC by far has the best.  It's cheaper and they are very professional.  I've gotten around in Lyfts my stay here.. Lyft is also cheaper rate then Uber.  

I will tow it to Tysons Corner and back to home. I take it too and from DC or I metro. Very convenient and inexpensive.

Thank you all so much for the advice. It is truly appreciated.