Here's another person who covers her box springs! I don't use a matteress pad (never thought of that) but I do keep an older fitted sheet on the box spring, then I lay the non-ruffled dust cover over that so the top and sides of the box springs have two layers of protection.
I have a thick queen-size bed. Very thick. I buy king-size bedding for it. The bottom sheet does not tuck in tight enough to "bounce a quarter", but my military days are, sadly, long gone and the slighty looser bottom sheet does not bother me anymore.
I do love the extra width on the sheets and blankets.
The corner garters never worked for us. They always popped off during the night.
I've always used a mattress pad on the mattress.