Alternative class feature at multiples of 4 (when ASIs are character-level-based)

[Ellyth]

Personally, I despise having ASIs as class features, barring the extra ones that e.g. fighter get. Absolutely hate it. I like multiclassing and ASIs/feats are just way too character-defining/enabling to awkwardly miss out on because your class levels aren’t multiples of 4.

The problem, of course, is if you houserule ASIs to come every four character levels instead of class levels, you wind up in a situation where those levels are dead for most classes, which makes them just too tempting to choose a breakpoint for multiclassing. I like multiclassing, but I don’t want to shaft single-classed characters.

So what I’d like is to have some replacement class features at those levels, to make them comparable to switching to a new class. I realize this is necessarily going to improve the power of classed characters; I’m fine with that. But what I want is to try to even things out a little bit more between multiclassed characters whose levels are neat multiples of 4, those whose levels aren’t, and single-classed characters. The inter-class balance is more important to me than balancing classes against monsters (I already have to massage that anyway).

Are there any products out there, or homebrew efforts, or even just houserules you’ve tried, that offer something for this?

[Pex]

An idea: Gain two of new skill proficiency, tool use proficiency, language known, another background perk.

[Talsin]

Are there any products out there, or homebrew efforts, or even just houserules you’ve tried, that offer something for this?

You could offer half-feats without the stat-bump (or even a +1 to a single ability score).
Maybe even a watered-down version of a different class feature, similar to the "Martial Adept" or "Magic Initiate" feats.

[Marcotix]

I'd just leave it as is- Multiclassers will have dead levels at 4, 8 ect. It's a minor buff to Multiclass characters, full class characters are probably fine without something being tossed their way.

I do like the idea of a bonus background though.