No. There are exceptions, like if you intend to penetrate the
"defense zones" that cover the ocean approaches to the
U.S., but for all intents and purposes a flight plan is not required.
The prime value of having a flight plan on file is that if you
don't make it to your destination, your odds of having people
go out looking for you are increased. However, VFR flight plans
can be vastly over-rated. Quite frankly, unless you fail to show
up at your destination, they don't mean much. And, there is a
long period between the time you give as your ETA, and the launch
of a search and rescue.
The best VFR flight plan, by far, is letting someone know where
you are going, with who, and when you intend to get there. Trust
me, they'll have more concern about your timely arrival, and beat
more drums than a government bureaucracy will. Nothing against
the good folks that work for the FAA, but they have incidents
of people not canceling their VFR flight plans every day. In almost
every case, the driver just plain forgot to cancel.
What are the advantages, or disadvantages, to filing a VFR flight plan?
The main advantage in filing a VFR flight plan is that if you
don't get to where you are going "they" will start looking
for you.
Maybe.
Well, probably.
After awhile.
Don't expect the Civil Air Patrol to launch into the skies
looking for your downed airplane, that may happen, but not initially.
When you don't appear at your destination airport and close your
flight plan, the FAA will call the airport and start asking around
to see if your aircraft is parked on the ramp some place. Then,
if your plane doesn't show up on that search, they'll ask aircraft
traversing your area of flight to monitor frequency 121.5 to see
if they can hear an ELT (Emergency Locator Transmitter) signal.
This is a device, usually located in the tail cone, that is activated
by a "g switch" when you crash. It emits a warbling
tone on the frequency until turned off or the battery dies. Depending
on the circumstances, it may be well over a day before a full
search begins.