i can't vouch for Fidelity. but folks on this forum seem to like it very well. I see no reason you can't use them to accomplish most if not all of what you want to do. If you are currently comfortable with 30/70, I see no reason you can't continue to use FIDO. I don't know what kind of "managed plan" you have, but I would think, within FIDO, you could move to a self directed plan - and still end up with 70/30 or whatever AA you wish to have.
Personally, I use Vanguard and "do it myself" as far as the various funds are concerned. Of course, I don't use them exclusively. Some of my stash remains at Megacorp's 401(k) (primarily, my stable value fund and what little remains of my matching stock funds.)
WHERE you put your money should probably be based on who you trust and also who has lower overall costs. HOW you structure your AA is still up to you. The only suggestion I have is to diversify enough to give you a chance to weather the inevitable storms. But don't diversify so much you can't track everything.
Pointed out by REWahoo, inflation is a major problem. One OTHER way to "beat it" is to start with so much in your stash, that "normal" inflation will not make a difference in your life style when you are 72, 82, and 92 (maybe, after that, who cares
I too consider myself very conservative. I know I have given up a lot of gains by not using the stock market more (I'm also in the 30/70 range). I made up for some of that by having a larger stash "than I need"- I hope. Another thing I have done is to work on maximizing my income streams from outside sources (I stayed a bit longer to get the max pension. I'm waiting until 70 to take SS. I will consider buying an annuity if I see value in that when the time comes.) I also have a small investment in precious metals within my portfolio. Most folks here hate PMs and I DO understand all the reasons. However, the theory says the correlation of PMs to "normal" stocks plus bonds is often quite negative (a good thing when stocks AND bonds both go down). I'm sure that's not always true, but it was an amazing thing to see my portfolio rise during the 2007 to 2009 stock market bust.
I'm sure folks on this forum are much better able to suggest an AA for you. Just understand that you are not the only one who prefers a "smooth" ride to a roller coaster ride. I can only tell you what I have done to get a relatively smooth - but not spectacular ride - for the past 9 years of ER. I won't give advice because YMMV.