"Stay on top of things" means to remain in control of a situation,

Here are some synonyms and similar phrases for "a wealth of experience":

▌Synonyms:
1. Abundance of experience
2. Extensive experience
3. Vast experience
4. Rich experience
5. Plenty of experience
6. Ample experience
7. Profound experience
8. In-depth experience
9. Significant experience

▌Similar Phrases:
1. A treasure trove of experience
2. A deep reservoir of experience
3. A vast knowledge base
4. A myriad of experiences
5. Well-versed in the field

These terms can be used interchangeably depending on the context. If you need help using any of them in sentences, just let me know!