Thanks all!
@Lana Lee - yes it's a single family. The SF Bay Area is likely too expensive to 1031 into better cash flow situation so I would likely need to explore out of the state, which I have not thought about at all yet.
@Aaron K. - good call on using the HELOC to fund improvements, and I had not thought of refinancing our primary down the road to help pay off the HELOC. Our cash savings would not reach the level we want for several years probably for us to feel comfortable, hence our desire to unlock some cash.
@Christian Wathne - I had not thought about getting into another property/set of properties if we sell one of ours, partly because we want to reduce the stress and time of owning/managing another rental. However if there are low-risk hands-off ways to do an out of state investment I would certainly be open to it, especially if it provided solid cash flow. Where might I research available options like this?