I have 4 colors of crape myrtle. Purple Solid white Pink Red/White mix

I have one of these lovely shrubs, and recently looked your question up in the AHS Encyclopedia. For deciduous viburnums, prune immediately after flowering.

If that's what you want to do then go for it. Cutting back shrubs is a good way to rejuvenate old plants. What is usually done is each year, and the time can be right after flowering, cut back the old shoots...the ones in the center. Do not remove more than 25% each year...so that after four years of pruning, you have an entirely new plant. Cut these old shoots right to the ground. You can tell which are the oldest shoots by the color of the wood. Viburnum snowball I remember having one in my backyard and the only problem we ever had with them was the earwigs were always around it.....possibly because the plant was situated near the outside tap and possibly the area there was moist from water leaking whenever the hose was used. Because we were on a septic system at the time, the grass grew mightily and we used more snowballs as a hedge at the back of the property which bordered a farm. I caught a cow once with her face in the plant....but she wasn't eating it...so I assume the flowers or the smell of them attracted her.

You certainly don't want any lawn/turf grass growing right up to the base of the plant - that's just a maintenance nightmare. For a truly 'natural' look, the plants should be connected by a single planting bed rather plunked down individually directly into the lawn or even with a small mulched area - that just looks random and disjointed. FWIW, mulching is the best thing you can do for your soil and ongoing plant needs so I would encourage you to get over your aversion to it. If you just can't tolerate the mulch, once the shrubs are unified/grouped into a single planting bed, you could underplant with a groundcover. This link will give you some place to start but there are many, many groundcover options available. Check online or at a better local garden center for selections suitable for your growing and light conditions.