I would put in some 'Ponytail' grass. I gave some of my baby ponytails to a friend who put them in pots with sedums and portulaca and they look awesome.

I'd do something bold and tropical, like maybe one of those red striped bananas. One year I underplanted one with Salvia glechomifolia, which has a sprawling habit and little blue flowers over a long bloom season. It was one of my favorite containers that year.

I use a trellis in mine for vines and then use other perennials or annuals to fill in around the bottom. Native Wisteria has worked well bloomed big recently and then will bloom on and off this summer. Coral Honeysuckle in another was beautiful (3rd year) and I used Gloriosa vine for summer blooms with it. A friend of mine uses clematis. I've planted some of the beautiful/colorful but less hardy elephant ears in them and just lift them in the fall. Cuphea/mouse ear and Cat's Whiskers have worked, but the cat's whiskers needs a lot of watering. Last year I had Hibicus acetosella 'Haight Ashbury' in one of them and that was gorgeous. Sweet potato vine fills in great and drapes nicely over the sides. Then in the fall I just took cuttings from it to winter it. This year I'm filling in with sun coleus so far, still trying to decide what else. I try to use a lot of color, texture and different heights. If you're out and away a lot in the summer or concerned about watering restrictions this summer you might want to think about something that's more drought tolerant as with any pots they do dry out faster. With so many plants in them I think the leaves tend to shed a lot of the rain water away from the soil too. I've also used the half barrels with fig trees, berry plants (to keep them from taking over an area), even a small veggie garden. I've used one for years with waterplants like duck potato, horsetail and water iris, etc. outdoors and last year buried one up to its rim in my greenhouse for waterplants. I toss a mosquito dunk in there as needed and sometimes some cheap feeder goldfish that's really fun for the kids (big ones too). Something that you really like but you know is invasive (rice paper plant comes to mind!!) works well in a barrel above ground or buried.
So about anything you can imagine you can do.

I agree with Karen, they're great for bananas, citrus or other tropicals! Just keep in mind you lose zones with an above ground container so if it's not hardy enough you'll have to dig it up or find somewhere to store it come fall and they're heavy to move around.

Some great ideas! I'm glad to know I'm not alone in the "What do I do this year?" department. I have a Coral Honeysuckle that I've had in a mid size pot on a small support for a few years now. It blooms beautifully every spring but it's bound to be beyond root bound by now,lol. I'm still on a well so I can choose drought tolerant or not. I wasn't very impressed with Back Magic EE the year I did that-not as showy as I thought it would be. The barrel is mostly viewed from a distance since we don't use our front entry much.

Shari, Black Magic really needs a lot of sun to show its beautiful color and it's a very thirsty plant in full sun. I've used Xanthosoma jeoquinii or Xanthosoma atrovirens 'Mickey Mouse' and they add a lot of interest. X. jeoquinii has incredible leaves but again the more sun the better. The leaves are kind of crinkled looking and the more sun they get the more they crinkle. Mickey Mouse is just too cute with its variegatd ears. Both of those keep well in a cool (above freezing) place in winter, just back off on the water when it's cold. The black stem EE fontanesii (sp?) is a beautiful elegant EE and hardier than most. It is my fav EE when it comes to showy.

I think the EE's with more reflective surfaces, like the fontanesii, do show better from a distance. I'm trying a new black cultivar from PDN this year with that quality. It was pricey, but I went in with a friend, each of us buying one fancy new EE, and we'll divide them in a few weeks so it'll be like two for the price of one. Makes it a little more palatable.

Shari, this is a good time of year to check out the big box stores for tropicals. They get in huge plants so your container would look filled out from the get go. Merry Bells and small flowered petunias also make good underplantings.

I've never tried any in/out tropicals mostly because I didn't know what would take full sun. I have a small start of fontanesii from a Fall trade with Ralph that has just woke up and started growing. Is it reliably hardy in the ground for y'all?

C. Fontanesii has been very hardy for me in 7a, but most winters I either cover it with mulch or leave a pile of leaves on it. It comes back even when I don't mulch but seems to do better and grow bigger faster when I give it a nice mulch. Later in the year it'll send out runners, once the tips point up and start growing new leaves you can always cut them off and pot up a few just in case you lose the mom.

I love to container garden, I like the flexibility to move things around and get different looks thru the growning season. I always have used containers especially around my doors and decks. As a rule I always use annuals, but this year I have a dwarf Cavendish Banana and a Dwarf Tangerine in containers for easier overwintering. As an aside, where are you finding half barrels? Haven't seen any at HD yet this year and I love the little watergarden idea mentioned here. I may try that one this year!

I haven't been this year but Kmart was where this one came from. I'm still thinking on what to plant...

I found mine at the nursery located at our Farmer's Market for $5 each on clearance several years ago in the fall (yep I bought all they had for that price, lol), but I have seen them at Garden Ridge in G'bro. They use to carry both the wooden half barrels and the plastic liners which is what I use. I think the ones I found are heavier duty than the ones GR has carried before. I've also looked at the small round ponds. I think they would work if you could find them for a good price.

I have a red Knockout in a barrel, and it is, quite frankly, a knockout! Last year, I found myself with an available barrel and a miscanthus gracillimus I didn't have a permanent place for yet. I centered it in the barrel and underplanted with purple, pink, and coppery-colored calibrachoa - it was absolutely gorgeous. After the calibrachoa were pulled in the fall, I had a barrel full of winter interest :)