@Alec Norman
Some thoughts for you based on my experience as an owner/landlord with properties both here in Arlington and in TX:
Its a terrific time to sell in NoVA at the moment. A great agent in our area can get you top dollar and potentially even multiple offers if your house is priced well and in great condition. If I was in your situation, I would sell tax free now and roll that $100k+ into multiple turnkey properties or even a small multifamily and get some serious cash flow going without having the hassle of managing your property yourself (or having that terrible feeling when tenants abuse or destroy something in a home you have cared for and loved). If you buy the right properties in the right market and set up the right property management, it IS possible to have your cake and eat it too - my A+ rentals in TX, for example, have appreciated nicely since I bought them and they continue to put a nice chunk of cash in my pocket every month.
Our market here in NoVA has terrific appreciation potential, for sure. But for me, I decided I would let my primary SFH be my appreciation play and use any additional money to diversify my strategy so I had a consistent source of cash flow. Once you have both, you have a lot of options. For example, I now have enough equity in my primary residence that I could use a home equity line of credit to finance a flip, buy an additional rental property outright, or invest in a multifamily deal. I haven't used it as of yet, though, and currently have no plans to, so all that appreciation is currently dead equity and isn't earning me much "trapped" in my one house. My TX properties, however, are not only appreciating nicely, but every month I also see a nice fat check, which I just save up and then reinvest into more real estate.
It all comes down to your comfort level and your objectives: what works for one person might not work for you. Either way, it sounds like you are in a great situation - having an appreciating townhouse in Vienna or $100k tax free to invest is a great problem to have!