Melanie,
If you believe real estate is the way to go for investing, you should consider purchasing properties in your IRA if you convert your 401K to either Roth or Traditional IRA. Either way, you will not be able to use that money until you reach the magic age, but I see no reason not to invest in multiple items other than Mutual funds.
My wife and I just converted our IRA's to Self Directed. She had a 401K that she converted to a Traditional IRA; mine has always been a Roth. We just purchased a Duplex in our SDIRA and so far I am pretty happy with the transaction that is seeing a return of 12%. We bought it 50/50 with each of our IRAs because 100% of the expenses of the property have to come out of your IRA--we can't co-mingle personal funds or we could be subject to UBIT. We have $80K property that if we had expenses come up that had to be paid, our IRAs would split the expense. We also invest in notes and mutual funds within the IRA money.
Basically here is how it works: rather than invest in a mutual fund, the IRA purchases and owns a property. The custodian (bank) that holds your IRA sends a check to closing for the property and you never touch the funds. The management company handling the property submits all bills or rental income directly to the IRA Custodian accounts and we never touch the retirement funding. We pay an annual fee for the IRA custodian and all little transactions under the account are included for the management of that property.
You can ask me any questions you like if you would like me to clarify. There are many other ways that you can get creative with the funds. You can write notes to other investors with those funds and let your IRA earn that way; there are many firms out there that sell notes. You can invest in a fellow investor's deal that they might not be able to fully fund on their own, but you could provide funding from your IRA and provide a note. That investor would make cash to use now and your retirement would grow. You could then borrow from that same investor out of their retirement to fund a deal you are working and you could earn income, while their retirement earns for them.
I am weighing the options of converting our other traditional account to Roth and I think we are going to. The penalty is steep, but which is worse: Paying $50k of your $150k now or $500K of your $1.5 million in 30 Years? Keep in mind that once you exceed a certain income level (I believe it is $180K?) you can no longer invest in a Roth. I like having the Roth now because in a few years I know I will exceed that limit and no longer be able to contribute.
All sorts of ways to use your IRA.