Certainly not too ambitious, although it will be a good bit of work and $ to completely re-plant your beds each and every year. And, truthfully, three quadrants of traditional rose garden type perennials and one quadrant of tropicals, will be, in my opinion, pretty jarring.

You might want to consider working with a mixture of perennials and annuals so you can get the best of both worlds. Make a list of perennials that you like and you know to be reliable in your area. Choose some perennials that will bloom in spring, summer, and fall. Then add annuals that complement those plants to keep the color show going when the perennials are not performing. Once you have your list of perennials, you will be able to see a color scheme emerging, even if it changes seasonally. Based on that, it should be fairly easy to select annuals to complement.

For instance:
spring bloomers:
Delphiniums or Larkspur (blues, pinks or whites)
shasta daisies (white w/yellow eyes)
peonies (reds, pinks, whites)
cranesbills (blues, pinks, whites)

Summer bloomers:
Echinaceas (pinks, oranges, reds, depending on variety)
Cranesbills, especially Rozanne (blue in spring, pink in summer)
heliopsis (yellows)
daylilies (pinks, reds, yellows, purples, whites)
phlox paniculata (whites, pinks, purple/pinks)

Fall bloomers:
Japanese anemones (whites/pinks)
asters (pinks, blues, whites)
Lobelia (blues/reds)

See a pattern emerging? You could easily choose pinks, whites, yellows, and blues as your scheme. Annuals that would work with these colors are petunias, salvias, marigolds, zinnias, ageratums, browallias...

Include some spiky flowers in each quadrant. Repeat some plants in each quadrant, even if they are different colored varieties. By all means, include bulbs for early spring color.

1). I have planted forget-me-nots from seed in the spring and had them bloom the first year for me. You can usually get wallflowers in the garden centers around here that are blooming. Then, those will go to seed. Second year, buy blooming plants again, and thereafter, you should have plants blooming each year.

2. Spend your winter reading and looking at garden books. In the interest of your budget, see what your public library has. If you don't have a subscription to Fine Gardening Magazine and/or Horticulture Magazine, you might want to get one. They are always full of great information and ideas.

3) If the tropical look is what you really want, go for it, but I'd say go whole hog, all 4 quadrants. However, make sure you either have plenty of money to replace plants yearly OR plenty of indoor space to over winter plants each year. Your winters are pretty long up there. :)

Donnabasket - thank you very much for your detailed answer and your suggestions. I actually slapped my forehead when I read your suggestions about making lists to combine perennials and annuals, and coordinate color schemes. Sometimes it's the most obvious things one doesn't see...:-)
But seriously, thank you so much for your help.

Marcindy, this bed sounds lovely - do you have any photos? Just curious as to how large it is, also, because that would certainly have an impact on how much work it would be for you.

Donna gave some really good advice and ideas, and I don't have much to add to it. Although I would suggest - if you don't already have them - trying some easier-care roses. The Knock-out series comes to mind, and is it the Carefree series? Certainly I suppose Japanese beetles don't care which roses they are eating, lol, but perhaps these lower-maintenance roses would allow you to still have some and have less work doing so. I'd hate to see you get rid of roses in this garden, although if I'm reading your post correctly you are not getting rid of all of them. Anyway, another thing to consider.

Good luck! And please post some photos if you have them.
:)
Dee

I'm sure there was really nothing you didn't really already know. It's just that we get so stuck with our frustrations, disappointments, and so caught UP with a new idea that sometimes we can't see the forest for the trees, so to speak:)

I'm with Dee. Post some pictures next year (if you know how. I don't, unfortunately.) I'd love to see what you come up with.
Happy Dreaming!
Donna

Marcindy, I'm with you on this. I switched to perennials (10?) years ago, but I'm getting tired of the dull times and lack of color. I'm switching to a combination. Perennials for "backbone" and annuals for more season long color. In fact, I logged in just to ask your own question.

I planted a flat of red salvias annuals to put in containers this past Spring, and ended up putting them in the perennial bed to fill a spot I had dug up to get rid of the mock strawberries that had infiltrated a groundcover area of sedum and dianthus. I also used annual yellow marigolds as a border near the lawn.

The constant color of the annual salvias and marigolds all Summer and Fall was so pleasing, that I think I want more annuals next year. I have a plant light stand that will hold 12 flats, so I have plenty of space.

And I've grown tired of having a couple (of 12) perennials of a type die every year and then having to replace them (when the new ones won't bloom for a couple of years).

So I am converting the flowerbeds to specific long-lasting successful perennials (like Autumn Joy sedum, coneflowers, coreopsis, asters, and astilbe, etc) and giving specific spots defined by edge-border for different annuals.

I just have to decide which annuals. I'll be watching this thread with interest!

And thank you, Donnabaskets for the suggestions... :)