I knew there were a few people out there that also overthink things. I usually try it both ways to see what differences caps changes make visually as well as any emotional impact that may be added, or removed. Apple’s style guide shows how tight regulations can hinder simple artistic decisions.
I named my company web design POP, Ltd. Co., or web design POP for short, and the capitalization is intentionally gimmicky. In some circumstances it may have some subtle psychological effect but in retrospect, I’d probably just have it as Web Design Pop. The correct capitalization shouldn’t have to become an issue, as it sometimes does on forms, printing jobs, and autocapitalization scripts. It makes it more fun to create logos for, however.
Using sentence case in titles looks misplaced, and just incorrect. Prepositions, “a” and “the” shouldn’t be capitalized unless part of a proper noun or at the beginning. If it looks normal, your title may be a little too long. Sentence case for subheadings is another story.