George,here are a few suggestions,and look at the clumps link,there are many pics there.
Dips
purple-Indian Giver
red-Stoplight
white-Joan Senior
yellow-Butterfly Ballet

Tets
red-Red Volunteer
white-Arctic Snow
purple-Strutters Ball
yellow-Golden Prize
pink-Corryton Pink
orange-Rocket City or Primal Scream

Look at pictures,pick what you like. If you have a question about them,we will help you out.You can look up the stats of your choices on Tinkers Database. click on online database and type in the name of the plant in the "cultivar" box.

Here is a link that might be useful: Tinkers Gardens

I have sparkling orange it is a really bright daylily. My husbands favorite one.
Jill

I have a couple bright Orange ones, the best eye catchers I have! -
this pic is not mine, I didn't get a pic of this one this year, it bloomed while I was away. Outrageous
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An oldie but goodie! Frans Hals
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Mauna loa
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El desperado is not really bright, but it is eye catching!
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As for purples this is the brightest one I have mainly because of the green throat, but it is kinda hard to grow, it bloomed for me and is now going to rebloom, but the fans are a bit ratty, and aren't very big. Malachite prism
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there are lots of them you could choose, it should be fun for you! Happy hem hunting! -Jessica

Eye Yi Yi always calls attention to itself.

As does Golden Compass.

Classic Edge, partly because of its tendency to have huge numbers of flowers every day (mine bloomed for over a month straight this season - every day multiple blooms)

Another clump of CE

Here's a few that scream in my garden:

Good luck -- Chris

This was a first bloom and the colors were much brighter than the photo shows:

I just bought 'Going Bananas' and I have to say, it catches my eye everytime I walk anywhere near it. The yellow is SO vibrant. It has a USDA zone rating of 3 -9, but I am in 7 so I don't have zone 4 experience... Mine is fragrant. Here are some of my pics - they have not grown to huge clumps yet, but you get the idea:

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Here are some of my brightest eye-catchers:

BRIGHT SUNSET (Tet, dormant, 36" tall, 6" blooms, Early-Mid season for me - strong, tall orange)

HEART OF JADE,(Dip, Dormant, 22", 4-5", Early - it blooms larger for me than its listing on Tinker's, which is 3 1/2")

FROZEN JADE (Tet, dormant, 25", 5 1/2", midseason; this color CUTS through the garden, it's really strong)

BREAKAWAY (Tet, dormant, listed as 30", but it's taller for me, closer to 36", with 6" strong orange-peach blooms, midseason; it has scapes like tree trunks, and it multiplies well)

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SPELLBINDER (Tet, Dormant, 34", 6-6 1/2", mid-late, darn near NEON in person, this picture doesn't do it justice)

I'm in the upper end of zone 5; I get a zone 4 winter every couple years if you go by low temps. These plants haven't minded the cold at all, and just keep thriving.

Laurel

Thanks everyone for your input.
Any suggestions for Bright Lavender daylilies?

wow,I injoyed this post with all these beautiful blooms.I love these reds and purples,but that Classic Edge is really gorgeous.I want that one.

Jean

Mary's Gold and Chicago Gold Coast are bright yellows that really show up and catch your eye.

Mauna Loa, Solar Power, and Hot Wire are bright oranges.

Christmas Is is a bright red with a wide yellow-green throat that is eye-catching. Highland Lord is another good red, a double.

Dark purples: Mountain Heights, Nordic Night, Night Beacon

Loved the pictures!!

Here are better pictures of 'Bright Sunset' and 'Spellbinder':

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BRIGHT SUNSET clump

SPELLBINDER

Here's a nice, strong pink, too:
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BORDER CROSSING

Laurel

the best pink i have is Setting Pink Sun
it is very strong bubblegum pink. not sure how to post pics on here so send me you email and i will send you a pic of it.