The 50 message limit on searches makes it difficult sometimes to locate messages and emails. I would appreciate more filters to be able to narrow down these searches when I can't seem to do so otherwise (for example, filtering by emails/messages created by me, created by a certain person, etc.).

As it is, simply making my search more specific isn't possible. There are some search terms that apply to 100s of emails/messages I've sent. In some cases, being able to filter when I know I made the comment (or a certain person made a comment) would help tremendously. Using advanced Gmail filters helps, except when it doesn't (i.e., comments).