First off, your choices of Musa and papyrus in particular are high water use, not moderate. So if you are putting all the landscape under the same irrigation regimen, plan accordingly. For bright green foliage color, I'd recommend things like coleonema sunset gold, choisya ternata sundance, lonicera nitida cultivars, aeoniums such as a. canariense or a.Sunburst. Not bright green foliage, but colorful phormiums, coprosmas, aeonium swartzkop, aloes such as a.striata,a. rubroviolacea, etc can also look good in a contemporary design. I like using things like dianellas, astelias, eucomis spp's, kniphofias, agaves, and various hedychiums or alpinias for that tropical/contemporary planting style. I also really like adding the weeping Mexican bamboo to this mix, or the blue stem bamboo, himalayacalamus to the mix. Ensete ventricosum maurelli and dwarf chinese banana and restios such as chondrpetalum tectorum and elegia capensis also have great form and add texture that will combine nicely here.

Low growers with high water and full sun are tough to think of! Low growing tropicals usually like shade.

In the shade under some of these plants, baby tears. Impatiens. Even the acorus prefers some shade.

Two plants that will do what you like but may not be to your taste are sprenger asparagus fern and agapanthus. Daylilies will do well with high water and full sun too. You may want to put something with loose and relatively sparse foliage under the bamboo, since it is very messy and the debris is not very attractive sitting on top of other plants. For annual filler, you can use nasturtium, which has a tropical effect.
Renee

Another pseudo-tropical option that I know is used a lot but I still love how it looks is Nandina. I have a couple down in my jungle area, and they really get lacy and pretty in shade. And Bahia, my papyrus do okay in the summer when the water dries up some. It grows in the swale area down in this jungly area, which is the lowest part of my yard, and all my water from the upper part of the yard drains down to it. So, for about 1/2 the year it's pretty wet, but during the summer it gets much drier. Does okay with this set up for me, anyway.

Patty S.

Some more plants to fit your theme might include neomarica caerulea, dierama pulcherrima, carex oshimensis 'evergold', cared tumulicola, fatsia japonica 'spider's web', strelitzia juncea, cyperis textilis, asparagus densiflorus 'meyers', wachendorfia thyrsiflora, and chasmanthe floribunda ductii.

One of the best and simple combo's I've seen in the bay area was Giant papyrus in back and purple Taro in front. Easy to grow-just add water.
The Family that did it is Pacific Islander. Looked great.

I wonder if you can grow Philodendron 'Xanadu'. I really like this one for filling in between palms, and it mixes nicely with colorful neoregelia bromeliads:

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http://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=2620