From the perspective of someone a little older who kept too much money in cash for too long, I regret not opening a Roth as soon as I started getting serious about saving, and even then I should have opened one sooner.
Does your job appear fairly secure (no guarantees, of course)? Are you in good health? Do you expect to keep your expenses level and continue at a healthy savings rate?
If so, take a deep breath, open that Vanguard Roth, and tell yourself you'll probably be fine. It's only $5500/year, and you have until April '19 to max out your 2018 contribution. Just start dropping 1k or 2k in per month until you max out 2018, then start working on 2019. It'll feel great! You'll probably end up saving more than what you can dump into the Roth, which you can then put into some kind of emergency CD/govt Bond/taxable brokerage account/ high yield internet savings account.
Even with a 1.5% difference between what you're currently getting and higher yield option, you're paying $120/ year for that "convenience & peace of mind". Over 4 years, that adds up to almost $500!