I would definitely get the Plaza
To be honest I don't think the height is that bad. The internal height is apparently 48cm. Only 2cm higher than the Barney cage (which I have and would jump at changing it for a Plaza but - have a cage already!) Assuming it's for a Syrian and not a dwarf hamster.
Main thing would be to have plenty of substrate to cushion any falls and I don't think it needs a full racetrack. If you were concerned about the height you could put strips of perspex or cardboard around the inside of the bars near the base - maybe 2 inch high - and put deeper substrate in, thus lowering the height.
Rodipet also make great labyrinth houses - large - almost full depth of the plaza cage - they're not cheap and maybe work out more than a wood shelf but then you get a house as well. They also sell little legs you can attach to the house so it sits above substrate level (and makes a good shelf height). And then a shelf at the other end. As long as any hard items are under or on a shelf and can't be landed on it should be fine.
Have to go now but will post a photo later of the labyrinth house as a shelf in the Barney and you can see the height effect and add 2cm!