Thanks DoubleDOwn, twinge, James, and Ozstache for the input! A couple answers to your questions, for clarification:
Home equity: The house is worth about $400K and we just paid down the mortgage to just under 300K, so we're about a quarter of the way there. We refinanced two years ago from 5.5% down to 4.5%. One thing we found in shopping it around for refi was that, in the DC area, most of those wild claims of absurdly low mortgage rates don't apply. Maybe it's that the banks know folks here have steady income (feds) and that drives the market up? I don't know, but we didn't really find any better offers from anyone we considered a reputable lender, and ended up just refinancing with our original lender, Wells Fargo. We've thought about refinancing yet again, or even getting into a 15-year mortgage with an even lower rate, but I wonder if just working on paying extra principal on our current loan is just about as good as messing with paperwork to improve the rate. In any case, at a minimum, I think paying at least some extra toward the mortgage is a GREAT idea at this point.
TSP: I'm currently kicking in about 10% of my gross income (around 10K/year) into the standard Thrift Savings Plan account. Got 100% of it allocated to the L2030 account (one of TSP's Lifetime funds that provides a mix of stocks, bonds, etc with an investment allocation that grows steadily more conservative as the horizon of the year 2030 approaches). Definitely going to increase that in the near future, as it's dawning on me that I need to take better advantage of that account, not to mention its usefulness as a tax shelter. TSP just started offering its Roth option this year (it's equivalent to a Roth 401K, not a Roth IRA) but, as one of you alluded to above, I'm still not convinced it's a great deal since I suspect we'll be in a lower tax bracket in retirement. In that case, wouldn't it NEVER make sense to use the Roth option? Maybe I've figured it wrong, but it seems the standard tax-deferred TSP plan is the better way to go, though I'm still researching/considering it. As an alternative, a mix is not out of the question: the annual contribution limit for 2013 is $17,500, which can be allocated between either the standard or Roth options, but you can't exceed $17.5K in the calendar year.
Student loans: my wife actually corrected me.... our students loans are about 1% on average, so we're paying almost no interest. I've almost pulled the trigger on just paying them off a couple times, but that low interest rate stops me. I know MMM preaches killing all debt, but isn't this almost a "good" debt to carry at this absurdly low rate?
More on us: I'm 37 and my wife is 32, so we can afford to take some investment risks that older folks cannot (or should not!). We bought both our cars cash so we have no car loans to deal with. We each have a bike and we've drastically increased the amount we're biking (DC is loaded with great bike trails all over the place, thankfully!). We even bought an old Radio Flyer wagon we found at a junk store and now walk to the grocery store (about a mile away) with Junior in tow, then plop him on the groceries on the way back. He seems to love it, though we get weird stares from folks roaring by in their 9 mpg German SUVs... they think we're crazy, we think they're crazy. Guess they're all independently wealthy already :-) So anyway, we're trying to emulate the frugality of our Depression-era grandparents to the extent possible.
On the 529 plan, thanks for the tip. Our little guy is just 1 year old, so we have some time till college, but we haven't set up any special accounts for him yet. Any money we've gotten, we've basically just socked it away in the ING savings account. How does the 529 plan (for Virginia, if anyone knows) work to reduce our Virginia state tax liability?
Anyway, thanks again for taking the time to share your thoughts. We really appreciate it!