I would say Vanda level light for these ones. I have my Hoya imperalis growing where it literally touches the glass of an unshaded South facing window. My only Erithrostemma is lauterbachii and it has a similar position in full unshaded Southern sun where it gets very hot, this is exactly what these plants want and if you can offer these conditions these are the first plants that should go there.
You could also consider adding a compact fluorescent bulb to boost the light for your other plants. These bulbs give off a good amount of light and a 23W daylight compact on for part of the day will really help.

Mike

Mike Thanks

For the high light loving orchids, a 4 bulb 54w T5 will be giving them their light this winter, but if I put these Hoyas under those lights as well, the lights would have to be adjusted too high to benefit the orchids.

So, I have one good South facing window that isn't blocked, and I hang my warm loving Vandas in it. And they bloom and grow fine, so I'll put these kinds of Hoyas in that window and hope for the best then.