I need some advice on what brand of unicycle to buy for a 61 inch woman. I have been riding 20 inches for long time and need more of a street/cruiser, but it seems that they are all made for tall people…any suggestions? I want a mid priced unicycle.
20" with a geared hub 
UDC makes nice Nimbus cruisers. I have this model (or at least last year’s version of it):
http://www.unicycle.com/unicycles/cruiser-24-inch/nimbus-ii-24-inch-unicycle-with-isis-hub-blue.html
The 200 mm seat post gives a minimum inseam height (crotch to floor with shoes) of 28". Is that still too tall for you? If so, you could cut down the frame without too much trouble and probably get another few inches. To gain an extra half inch you could wear shoes (boots?) with thick soles.
What is your inseam? What distance to you set the pedals from the seat?
Shorter cranks have the effect of minimizing the inseam requirement without lowering the seat.
Scott
You should be able to make a 29" unicycle work for you.
One way to find out is to measure the distance between the bottom of your seat and the top of your tire on your 20"
subtract 4.5" (11cm) from that number.
This is approximately the distance you have to work with between the tire and seat if you are using the same sized cranks on the hypothetical 29er. In this space you need the frame crown, a bit of seat tube, and your seatpost clamp.
If you end up with a around or above 5" you can easily make it work with only shortening the seatpost and maybe the seat-tube. Less that that and you are looking at using shorter cranks (which you might want to do anyway if it is for the road) as well as shortening the seatpost and frame.
Don’t let the idea of shortening a frame scare you. many people do it.
I’m about the same size as you are, with an inseam of 28", and just bought the 29" Nimbus cruiser. I cut 2 inches from the frame and 5 inches from the (300mm) seatpost and it’s just fine.
You could probably cut another inch off the frame and another half an inch off the seatpost so it goes down all the way. Oh, and I have the standard 125mm cranks.
think about your inseam and crank length, not your overall height. Women also tend to have longer femurs than men, so comparisons are trickier.
You could ride a Nimbus 36 frame, if you cut off about 1.5" inches from the frame seat post tube (cut off enough to leave 1" of seat post tube insertion).
My wife is 5’2" (I think…)
corbin