Will be based out of shenzen for two weeks. What are some nice and convenient day trips, besides hk?

Well, it can be a good choice to travel in SZ. Window of the World, Splendid China and Ocean World are the mut-see attractions there. If you have enough time, Dameisha and Xiaomeisha Resort are also worthwhile traveling.
About the tour itineries, you can refer to the website to know the details:
https://www.travelchinaguide.com/package/shenzhen.htm