It looks like you're off to a good start, since you're father was involved with REI. I like the idea of a cash-out refi on any of the properties to pay for additional asset purchases. Then, let the cashflow from those add up to pay for things like a new kitchen. However, this is a question that only you can answer, since happiness means different things to different people.
As for the kitchen, using the ideas from rich dad, poor dad, I like the idea of allowing an asset to pay for those type of things-- of course, this takes discipline and has tradeoffs. For example, when we moved into our new home in ATL from Buffalo, NY, we acquired a kitchen from 1989 and a backyard that didn't have any grass. Instead of investing this money, we opted to spend it on tearing down some trees, grading the backyard, and updating the kitchen. We are comfortable with that decision. But it comes at the cost of not being able to purchase another property this year.
Regarding your question about converting your home into a duplex, I think that depends on whether or not the rehab to do that would be worth it. That is certainly one option. But you may want to talk with a GC to understand the total costs and then estimate a proforma to determine the return. Another option would be to sell the house for a large profit and use that money to purchase other properties that are already setup as MFR.
Of course, I have a friend who is convinced to not use leverage and instead simply pay all debts down as fast as possible. He's a big fan of mmm (Mr. Money Mustache).
I'm not sure if this is a help for you or not. I know its a bit ambiguous, but it sometimes just comes down to which trade-off's you'd prefer. For me, I don't mind using some leverage, when possible-- especially while the interest rates are still low.