I'm a fan of SCHB. For that level of assets, I would invest in SCHB and SCHZ based on your preferred allocation. 50/50 seems to be a decent split for your age based on normal metrics.
My personal belief is that everyone who has not invested through a downturn should take the allocation they're comfortable with and add 5-10 percentage points to the bond portion. Once you've invested through a downturn and are comfortable with the associated losses, then you can move it back up. This is just my personal opinion, and not a widely shared one.
As your portfolio gets larger (maybe north of $20Kish), I would add a few other Schwab funds such as SCHA (small-cap), SCHF (international) and SCHH (REIT's). The added complexity to your portfolio isn't worth it at this stage, but it's something to think about as it grows.
Most importantly, once you've decided what you're going to do, write it down in an investment policy and stick to it.