Behnke's usually has both. But you might want to reconsider getting the tulip poplar in a large size - or at all. They grow incredibly fast and will settle in and put on growth quickly, so save your money and get a smaller one. They also drop wood just as quickly, so not really a great tree for a small lot. Or a large lot. They make a mess and can do damage with the fallen branches in each storm as they mature. For a small lot, consider Parottia persica, that's a really nice specimen tree.

Sun Nurseries -- worth the trip. 1000's of trees, shrubs, etc. Great pricing.

Can I throw in a plug here for a cucumber magnolia? Wonderful NATIVE to this area, easily gets as large as a tulip tree, but quite rare to see it. Not that tulip tree is a bad choice - it is a food tree for tiger swallowtails.

Willow oak doesn't really have any extraordinary qualities to recommend it.

Re Sun Nurseries, their service area ends well north of our house and I hope to buy a tree that would be too large for our car. Any other suggestions for a place that would deliver to the beltway area of Silver Spring? Thanks!

Rent a small truck from a Box store for $30-50?

There are nurseries specializing in oversized trees. About ten twelve years ago I bought a zelkhova with a trunk 4 inches in diameter for a couple of hundred dollars. I imagine prices have gone up. I am told thre is a real price break at 4 inches. Bigger than that and prices really rise.

Such nurseries however are not really retail nurseries. You'd be an afterthought. They service mainly developers.

You might be better off buying from Behnkes, who'd get it from a dealer.

When I bought my big trees I waited until fall. The summers in our area are much tougher than the fall. You'd have to set up a regular watering program etc.

I also bought a 2 inch willow oak. Worked out--it is now largish---but I wouldn't describe it as wider than taller.
Furthermore, it doesn't really shade the house. I planted it near the property line to shade the patio. It will take a long time before it shadows my 2 story house.

Tulip poplars are a major pain when they loom over a house. I had several big ones hanging over my last house- never again. They drop flowers on the roof in the spring, the small elongated seeds in the summer, then the leaves in the fall. Three seasons of gutter cleaning. They also shed branches nearly continuously. The only thing they have going for them is fast growth and nice fall foliage.

You are going to need to live in that house a LONG time for any new tree to give you substantial shade. You will need to deal with that particular trees problems all those years...

Another vote NO on the tulip poplars!! They also throw sap against the house, windows, decks and then the ants go after the sap. We just cleaned up branches - that were the size of trees-from the storm that split off my neighbors tulip poplar tree. They are messy, nasty, dirty, and ulgy trees. I would remove them all if I could.