What about Cymbidiums? I have seen very large ones with very large flower stalks. Some are fragrant too.

Mike

We have quite a few Cyms and keep them in a separate area as they are mostly in large pots and need watering. This area is WILD and we don't want to have to cultivate it so it needs something pretty tough. - Ian.

Rather inartful reply, I keep editing to add new things so it goes from paragraph to list form.

Some of the largest orchids known are Grammatophyllums. I wish I knew where I could find the picture, but there was one I saw years ago of a lady standing next to hers (either tigrinum or scriptum), and it was twice her size. Schomburgkia/Myrmecophilia are also pretty sizable. There is another, name escapes me, that is rather xerophilic...it might come to me later.

Epidendrum pseudepidendrum might also interest you. As are many Coryanthes and Stanhopea (both have downward dangling spikes so MUST be mounted).

Several Bifoliate cattleyas can get fairly large (~4 feet/1+ meter tall).