@Steve O'Keefe Looks like you've made a decision on what to do, but I wanted to throw my two cents in. As has been brought up several times in this thread, I think ROE (return on equity) is the metric you really want to look at for your situation. The question is, what kind of returns can you make if you put that equity to work in another investment?
In a perfect world, where you don't care about risk, you would leverage everything to the hilt (75-80% LTV) and keep as little equity as possible tied up. Then you could invest the equity you successfully freed up from a cash out refi into other assets that generate a return greater than the mortgage rate (which shouldn't be hard to do in the current low interest rate environment). So you would do a cash out refi on your houses to a 30 year mortgage at 75-80% of value and reinvest the money into other rental properties, syndications, stocks, bonds, whatever.
However, we don't live in a perfect world, and everyone has to determine how much risk they're willing to take on. For me, I don't ever want to leverage a property up to the point it no longer cash flows. If you have to come up with cash out of your pocket every month just to pay the mortgage, you are at high risk of default should anything go wrong (lose your primary job, big repair bill, extended vacancy, etc.) And it looks like from your numbers you are at about a breakeven cashflow right now, so I wouldn't recommend increasing your leverage anymore.
There are two main components to your return - cash flow and appreciation. So taking your numbers at face value, you've got roughly $500k of equity earning approximately a 0% cash return. If you look at the Case Shiller data, San Diego has appreciated around 5.5% per year since 2000. So if you expect that to continue, on a combined property value of $925k that would be $51k per year in appreciation gains, for an overall return of (0+51)/500 = 10.2% per year.
That's not a bad return, but it is 100% dependent on the rate of appreciation, and my crystal ball is pretty fuzzy as to what that's going to look like in the next 5-10 years. But if you don't need the money now, San Diego is probably as good a bet as any to outpace the national home price appreciation rates over the long term.
The other option is to cash out and put your $500k of equity to work somewhere else, maybe in turn key properties in the Midwest where appreciation is a more modest 2% (every city is different - I used Chicago to come up with 2%), but your return is weighted more to cashflow than appreciation (less risky). Let's say you can get 10% cash on cash return from your $500k, using it to make 25% downpayments on $2M worth of real estate. So now you are bringing in $50k per year in cashflow and $40k per year in appreciation, for an overall return of (50+40)/500 = 18% per year.
Of course these are just examples with very rough numbers. Things change year to year as your equity position changes and you pay down mortgages. But the point I'm trying to make is that you are in a great position regardless of your decision as long as you don't overleverage and can at least achieve breakeven cashflow.
Hope that helps as you think through your decision. I have been thinking about this a lot myself. For my own portfolio, I am starting to selectively sell off some of my houses that have appreciated a lot in recent years (and where the ROE is therefore pretty low) and moving that money somewhere I can get better cashflow. But I also like the market I'm in (DFW) as it has strong economic fundamentals, so I'll probably keep some of my rentals here even if on paper I could increase my cashflow elsewhere.