Mary, I'm focussing in on your 'not too bushy'comment and therefore discarding most of the Miscanthus sinensis cultivars. For me the least bushy of these is 'Strictus'(porcupine grass), also interesting for it's horizontal striping.

Several Molinia caerulea var. arundinacea cultivars are tall, bushy foliage is held in the bottom third of the plant. Choose any of the tall cultivars; 'Skyracer', 'Karl Foerster', 'Transparent', 'Windspeil', etc ....

Or, on the slightly shorter side either Panicum 'Heavy Metal' or Calamagrostis 'Karl Foerster' would give you the tall, stiff, upright look. (for my money these are the best if you are looking for something strictly verticle)

On the other hand, if you want to go REALLY tall you could choose Arundo donax (plain or variegated), Miscanthus giganteus, or Saccharum ravennae. All of these get 'wide' in time but they have a more skeletel form rather than 'bushy'.

A.

Not as tall, but easily up to 4 feet in foliage height, are two nice erect annual grasses:

Setaria faberi, Giant Foxtail. Very fast growing, bright green foliage and 8" nodding foxtail-like seedpods.

Pennisetum glaucum 'Purple Majesty,' Ornamental Millet. Very fast growing, looks like dark purple corn with erect 10-12" almost black seedheads.

Both can hit their heights from seed in a single season, but both need to be watched for re-seeding.

Thank-you both for your suggestions. I will certainly follow up!