Tammy, do you mulch? If not, after rejuvenating the bed, I do recommend you try mulching.
As for now, you need to at least dig out stuff that is hidden and place it somewhere else, and do something with the weeds. Either dig them out or Cut back nicer plants leaving weeds and cover the nicer plants - then you can carefully spray some weed killer on the weeds. You need to be very careful doing this. I'd say it is last resort...it's a very big bed.
What plants could be coming up now? Anything that could be damaged?
Lastly, I'd divide if need be, and put compost on/in/around everything and then mulch heavily.
Frankly, if it was me, I'd dig the whole thing up, weed it, compost the heck out of it, replant and then mulch it really well. You should still get spring bloom from bulbs, as long as they get chill hours they should do OK.
It's a big job, I'm sorry you have to go through it!!

I was worried that by digging I would lose somethings that werent growing, but after I think about it, most of the stuff is either in stages of dying back or still blooming some. The only spring stuff that are gone (that i can think of) are the bulbs.
I tried mulching once, but there was so much bare area, that i needed a LOT of mulch, and it didnt seem to last long. I hate to look forward to this, but its prob the only way to fix things. I like the look of groupings of flowers, but mine seem to sprea around with only a few things here and there.
Tammy

I agree with GGG. If you really want to get the bed in shape, everything needs to come out. Then get the weeds out, till in some good ammendments, replant and mulch heavily. You'll be glad you did even though it will be a lot of work.

Do you have any garden friends that could help you and maybe take home a few plants that you might be able to divide while digging up? Maybe a plant party is what you need! Whenever I have a fairly large bed to dig up, I always invite friends and divide plants along the way. It make it go so much quicker and certainly makes it feel a bit less like drudgery. Good luck!!

To get rid of that spotty bloom here and there plant larger groups of each type pf plant. I plant groups of three. In larger beds one can plant groups of five. Also large beds can look more pulled together if one repeats a planting group or two. I know it is tempting for me to plant as many different kinds of plants as I can but that can lead to a chaotic look.

If you replant move the daffodils back from the edge a bit so you can plant a later growing perennial that will cover up the dying daffodil foliage, and at the very edge perhaps something trailing over the wall. Or leave space to add annuals for the same purpose.

"It is about 6-8 ft deep by about 60 feet long".
I'm having a panic attack just imagining rejuvenating that size garden! lol. Only because I did just that last Summer-fall.
I pulled out some stuff, then carefully (yea right) sprayed round up every other week or so. The garden looked like poop for the whole growing season, but it was DONE :).
I put down tons of mulch, very expensive but I didn't want to go through that ever again.
Is you garden flat? If so, then to save money put an ad on CL to see if you can get old news papers, bagged leaves, etc. to help on the cost. I couldn't go that route myself because mine was a ditch garden.
Stray weeds pull up like heaven in the mulch and I only had to water new plants. I can't say enough on the wonderfulness of mulch!
Once your garden is reclaimed your going to be sooo happy you bit the bullet and got it done. Sure you'll lose a few plants but you will be much happier in the end.
Good luck! Oh and with round up, you don't need to till. The worms will do all the work under the mulch.
:) Laura

That's too much to take on at once- at least, it would be for me. I'd divide it into three sections and do one at a time.
Renee

I have tackled this type of jobs a couple of times. I've known where the plants are located and snug several layers of newspaper around the base of each plant and layer them in the openings and cover with mulch. The newspaper smothered the grass and weeds while helping the plants you want to keep. Keeps the moisture level more stable. I've never done this where blubs are planted but I have read where they come up through the newspaper. That I can't speak to. But if you know where the bulbs are located then you could dig them out and replant after you are finished with the other job. Might be easier and you could do a lot of that work farily quick.

I put cardboard down and mulch on top of that, here in Texas newspaper doesn't seem to do the job. It works great, you'll get some weeds, but as auntyara said, the weeds are so much easier to handle!