I agree with previous posters about using sashing.
There is an interior decorators comment "Nowhere to rest the eyes" and sometimes if you look at house interiors in magazines (particularly country style) there are so many decorator items and collections crammed into one room that you have difficulty focusing and enjoying any individual item.
I think some quilts can be too crowded as well; the red sashing suggested will be a good strong design element and allow each individual block to be "read" and appreciated.

Personally, I'd use all black - no other accent colors - just black around all the comic patterns. Let the pattern of the blocks speak for themselves. Black in a quilt can be striking!

Try an auditon: Just place some loose black fabric between your existing blocks and see how the blocks 'pop' out at you.

Shari

I really like this quilt for a "superman" or "super hero" - I think the idea of putting the red sashing between the blocks would slow your eye down when looking at it. Give it a try, you might like it better. Great job.

I wouldn't like it either, but I'm not a Marvel Comics fan. If your hubby is, then you've done a fantastic job.

I kind of think what's going on with this quilt is more emotional than it is the quilt. It is a very vibrant quilt, first of all, but I happen to love vibrant. I also am disappointed in all the quilts I make because they never seem to live up to my vision of the quilt. The truth is there's nothing wrong with the quilt. It's my vision of the quilt that is the problem. Also, it's your husband, and if you love your husband (I'm assuming you do) you want the quilt to be absolutely totally and completely perfect. However, there is no such thing as perfect. It doesn't exist. I would suggest, like other people have, to use sashing between the sections that is plain fabric. I would suggest black. Black acts like a frame. In any event, I'm sure your husband is going to love it because you made it.

I would use 1/2" black sashing and then a 2" border sashing around the black using a solid neutral color (not white). It will take away a lot of the clashing colors.

As a guy I like the collage without the sashing but I couldn't tell you what he likes. You have to ask him. Lay out a couple of setups for him to choose from and then do it that way regardless of how you feel about it. After all if it was yours you would have flowers on it. ( Exaggeration there just to make the point).

Comics are about action and the panels are deliberatly complicated with a lot of detail. Sashing would take some of that away and loose the flavor to my way of thinking. You just gotta ask him how he wants it.

I agree with using black as your sashing and border. As previously stated audition it first, but I think this would be more calming.

Ha! He requested the quilt, chose the fabric, agreed with the pattern, but I didn't like it so I haven't thought to ask his opinion on options for finishing it! So, that is now next on the list. I amaze myself sometimes with how dense I can be at times...

Logofflater made a great point, I know my husband has a different take on things and what is visually pleasing. For me, I like the idea of adding a staggered vertical black sashing strip to each of horizontal sections and then adding a black sashing between each of the 3 horizontal sections and using the same sashing as the first border. The sashing could mimic the breaking up of the frames in comic books. But, I have a feeling your honey might like it "as is".