IAH is a big airport in a big city. Houston distances make ambitious layovers fragile, so keep the plan close unless you have a generous window.
What to do with bags
Do not assume airport storage. If your airline will not take the bag for the onward flight, design the outing around keeping it with you.
Leaving the airport
Nearby hotels, restaurants, and north-side neighborhoods are more practical than a full downtown or museum district run for most layovers.
Getting back through security
Build extra return time for freeway variability and terminal movement. IAH rewards boring buffers.