Random thoughts…
You can lose a lot of width from your compressors and limiters and this varies quite a bit from product to product. Some compressors have a dual-mode that resolves this issue.
Some limiters have channel linking that is more flexible than a toggle like dual-mode. FabFilter Pro-L is a good example.
Waves Center is a great plugin to look into.
EQ’ing left and right channels slightly differently will generally enhance the sense of a wider sound. A couple options in this department include SPL Passec and FabFilter Pro-Q.
Some mid-side plugins let you ignore low frequencies or even sum them to mono.