HCM in 2 1/2 days

We only have 2 1/2 days in HCM Feb 13-15. We are booked at Lavender Hotel across Ben Tanh Market, where we arrive mid afternoon on Feb 13.

We will go on the usual city tour (which is part of our tour package) on the morning of Feb 14. What places could we visit outside of the usual tour circuit in the afternoon?

We plan to visit the Cu Chi Tunnel on Feb 15. Is there any place you can recommend we go after the Cu Chi Tunnel? Is it good to combine Cu Chi with Mekong River?

Thanks for ur help in planning our HCM sojourn.