Hi,
Ever think about an Aloe vera plant? Beautiful color, relatively compact (if you de-pup them regularly) and they send up lovely delicate stalks of beautiful pink-coral bell shaped flowers...btw if you plant them outside the humming birds love them!
Agave 'Bllue Glow' is another nice one. Gets a max of 1.5 - 2.5 feet tall and maxes at 2.0 -3.0 wide. Usually solitary with no pups. Beautiful dark blue-green with yellow edging and red tips. When back lit by the sun it look like it has a 'glow' about it. Loves the sun and heat and is drought tolerant (in case you forget to water.
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I have another small Aloe in my yard. Very tiny, tiny guy. Not sure what it is called but it would be perfect! A few inche wide and a few inches tall. Grows slow and probably would max our at 2.0 feet wide and tall. Nice dark green and 'bumpy' texture.
I'll post some photos in a bit of these plants.
AG