I am flying in and out of IAD with my 4 kids in August and renting a car for 2 weeks. We arrive at 11 pm and plan on staying at a hotel for the night and driving to our destination 4 hours away the next morning. I have booked a car for pickup at DCA and return to IAD (inconvenient, but saves $400).

Are there hotels in DC that have complimentary shuttle to BOTH IAD and DCA so that we could take the shuttle from IAD that night and then I could take the hotel's shuttle in the morning to DCA to pick up the car and swing back to pick up the kids (don't worry 2 are over 18 ) at the hotel?

I have read about the public transpo options but was hoping I could find a reasonable hotel with the perks I needed. Thanks!

Welcome to FT!
I don't believe there are any hotels with shuttles to both airports.
If I were a hotel close to DCA, it would be a very expensive undertaking to run a shuttle to IAD.
You will need to take public transport or a taxi to DC to pick up your car.
Why aren't you renting from IAD?

If I were you, I'd choose a hotel closer to DCA. That way, you can take a cab from IAD and avoid any long, late-night shuttle waits (and daytime traffic), and you'll be where you need to be in the morning.

Shuttles serve hotels close to either airport but not both. As noted, the distances are great. Need to check the hotel Web sites. I don't think you can get a shuttle from DCA to even Rosslyn, but Metro works quite well. Cab from IAD to DCA will likely be expensive.

Since you'll presumably not get out of IAD until close to 11:30, after disembarking and getting your bags, you could stay near Dulles the first night (verify in advance that the hotel's shuttle runs that late; there is a Marriott almost across from the terminal), then take the Washington Flyer bus to the West Falls Church Metro rail station (uses the airport road, I believe, so traffic shouldn't be a big factor), and from there to DCA to get your car. Might as well wait until after rush hour, not just due to crowds on the Metro but to avoid traffic when you leave DCA (we don't know where you're going to). Besides, you'll probably get to bed late at night. If the cab fare of maybe $70 to a DCA area hotel doesn't phase you (maybe you can think of it as compared to the $400 you say you'll save by renting at DCA vs. IAD), staying near DCA would be the optimum, as you might not get to your hotel much later than if you stayed near IAD and you could take a leisurely trip to DCA the next day (by Metro if the hotel doesn't have a shuttle)..

public transit for 5 or 6 people will not be cheap. the shuttle bus from IAD to metro, Washington Flyer, is $10. Depending on the time of day, you can expect to spend $5 or so per metro ticket, including the new $1 paper ticket surcharge. That's already more than the cab cost of $60-70 per person to get into DC.

Take a cab.

I am willing to wager there are a few hotels in tysons corner/reston/fairfax areas that do offer shuttle service to dulles and to the nearby metro station...or if you are an elite level memeber they will do that for you.

Don't know of any DC hotels which offer free shuttles out to IAD. It's 30 miles out Route 66 and the Dulles Access Road.

With 4 kids, you are also over the max for a standard DC/VA cab. You can book an SUV through Red Top Sedan (not taxi, but Sedan) and total cost for an SUV will run roughly $90 all in.

I concur with the stay at Dulles the first night, then its a matter of what your time is worth. There is a MetroBus that goes about once an hour from IAD to Roslyn Metro, then transfer to the metro blue line and get off at DCA. That is likely the best public transport option that is available.

The cost of the 5A bus went up, and so are metro fares so i don't know the actual cost. Check the wmata.com site for fare and schedule

I've taken the metro bus. It's only once an hour or so and not easy to find at Rosslyn. Dulles is a bit easier. It's basically express, but it is still a city bus...comfort is not its goal.

Can someone explain to me how it saves $400 to rent a car for 2 weeks at IAD and return it at DCA?

However assuming its true, for the $400 saved, just take a cab

A cab is ~$65 OW inc tip; maybe a tad more for more people & bags

Can't you leave the kids at the IAD hotel (is one old enough to sit for a couple hours) while you drive it back to DCA and cab to IAD?

something doesn't sound right here

I don't think there are any IAD properties that have free transportation to the metro

What tyson's property has free IAD shuttles?

It is IME always just about the same price to rent a car at IAD as at DCA and there is never a drop off charge with any major agency. I do it all the time in one direction or the other and I am just as puzzled as Trojan Horse about a $200/week difference. I visit the area every month and rent a car every time. That $400 number is inconceivable to me.

Note that the 5A MetroBus on weekdays runs every 40 minutes most of the day, and every 30 minutes during the morning and afternoon/evening rush hours. It runs about once an hour on weekends and holidays. The schedule is at http://www.wmata.com/bus/timetables/dc/05a.pdf

While just about all Metro fares (bus and rail) went up on 7/1/2012, the cost of the 5A and B30 airport express buses did NOT go up. They still cost $6 per person - using cash or SmartTrip card. Note that the senior fare (age 65 and up) is just $3 - you can flash your Medicare card to get that reduced fare.