Leaving leaves on grass generally kills the grass.

MULCH is not supposed to break down fast. It's purpose is to slow down evaporation of water, suppress weeds, and keep the dirt under it cooler or warmer. If it broke down quickly it would be useless.

I'd leave the wood chips where they are, and put the leaves over the wood chips if they will stay in place. If they won't, make a cheap compost bin, dump the leaves in it, and let them decompose over the winter.

Next spring, just dig holes for the plants, or rake the mulch back to plant things like lettuce that you scatter.

If you composted the leaves, spread it over the wood chips in one or more beds. I just keep adding layers of organic stuff and the dirt improves itself.

Here is a link that might be useful: Cheap compost bin

The wood chips will break down and will help the soil. The smaller the chips, the faster they'll break down. In some ways, it's a good thing to have mulch that breaks down slowly because it doesn't have to be replaced as often.

If you leave the leaves on the lawn, they can smother the grass, but if you have a mulching mower, you can mulch mow the leaves into the lawn and they'll help improve the soil. Of course, if you get so many leaves that they're too thick even after mowing, that's not an option.

Leaves belong in the grass as long as you can get the mower though them at least

What are you growing in the beds woodchips definatly break down to very nice soil it just takes longer if you can slide them aside to plant I would just leave them there

In MN a heavy muched be doesn't unthaw very fast so you might need to pull them in the spring if you have early things to plant

@ Jonas: mainly I have perennials in the beds in question. So that's what I'm worried about . . . will the perennials manage to poke through. I guess I need to mark them well while they are still alive so I'll know where to possibly pull the mulch back to let them through.

I don't do to much with perenials they are typicaly mulched extra heavy in the fall leaves or straw would be great for that don't remove your wood chips they will be fine under there

In the spring after the weather warms up the extra layer is pulled aside I do have some tulips in wood chips they grow though there just fine I pile a little snow in them for insulation

If you watch the mn forum on here there is always some posting when its time to pull spring mulch there also seems to be a lot of perenial growers on there
It might be a real good idea to put some sticks where the plants are so you know where they are in the spring

There are several factors that determine how fast your mulch, no matter what is used, will be digested starting with how healthy your soil is. If you have a good, active Soil Food Web they will digest your mulch (provided it is not stone or rubber) fairly quickly, but that then depends on the type of material and wood chips can take longer then would shredded leaves. Thickness is also a factor, because the more there is to digest the longer it will take, but in some of my beds wood chips 4 to 6 inches thick get digested in 2 years.
Shredded leaves are an excellent mulch, although in my soil the shredded leaf mulch I applied last fall is now gone leaving the soil now bare and exposed to the ravages of the sun, wind, and rain.
There is no need to remove a mulch from a planting bed, unless your soil is in such bad condition that the plants have a difficult time growing. I would put shredded leaves on top of the wood chips. I find that the soil bacteria apparently work on the easier to digest leaves because after spring I see few, if any, leaves and only see the wood chips.
Leaves, left whole on grass, can keep the grass from gettng access to the sunlight all plants need to grow so whole leaves could kill the grass they cover. You can mulch mow those leaves into your turf and the soil bacteria will move them into the soil for you feeding your grass so it grows better next year. Joe Vargas turf grass students, back in the 1980's, mulch mowed leaves into a turf plot at MSU and found the grass in that plot (nothing else was done except normal watering) grew greener, thicker, faster than any other grass plot they had.