As others have implied, 3-5 years is not "long term." Modern Portfolio Theory equates risk with volatility. I have a lot of trouble with that for truly long-term investments, but for 3-5 years IMO it is a good way to look at things. So, the implication is that equity investments are off the table.
I would not consider MMF or other short-term liquid investments because paying the yield penalty for liquidity is has no value for me. If it were me I would consider:
A diversified portfolio of investment grade US corporate bonds with maturities to suit. "Diversified" means at least ten issues with no sector concentration.
TIPS. Depending on your expectations for inflation, TIPS may be a good way to (partially) protect the buying power of your funds while earning a small real return. "Partially" because the inflation increase is taxable, but so is every other alternative. No state taxes, though, in any state AFIK. You can probably just buy one issue with a maturity date to suit; no screwing around.
Govvies. No need for diversification here, just buy notes or bonds, maybe just one issue, that mature to suit your needs. Again, no state tax.
Brokered CDs. I am not a fan of CDs because, at least lately, you don't get enough extra yield to justify the redemption inflexibility. But many people like them and with FDIC insurance they are a safe as any government bond.
Floating Rate Funds like SAMBX. We have been holding low- to mid- six-digits of SAMBX for several years now, getting around 4% and feeling safe, but these funds are arguably riskier than investment grade corporates. Since these are often ETFs you get liquidity for free. Some of the floating rate funds are leveraged; I would stay away from those.
The bond desks at Schwab or Fido can help you make and implement a decision. It may feel a little daunting if you have not done this kind of thing before but it is really easy.