Doug Clark wrote:

: ?Would it be worth doing or should we just fly?

Depends on what you like. Some people like to see and experience
a bit of the country this way, away from the usual tourist traps,
others think it's boring. However:

: ?Can we get a rental car or must we take the train?

Under absolutely no circumstances use a car. Some parts of Russia
are not the safest areas for tourists and a stolen rental car might
be you smallest problem.
Apart from that: Missing knowledge of Russian is a point to discuss,
but if you cannot read cyrillic letters, you'll be lost if you have
to find your way on your own.

In any case, avoid Belarus if possible, it's close to a dictatorship.
Check with your ministry of foreign affairs, they have detailed
security information for traveling abroad.

: ?Maybe we should just stay around and see Corse & Sardinia & Sicily
: rather than taking off up country?

Maybe. It's closer, so you have more time on location.

The area around the Baltic sea is probably best explored by ship on its
own, there are many cruise ships and of course regular lines, too.
On a cruise ship, you can -in addition to St. Petersburg- visit Finland
(Helsinki), Sweden (e.g. Stockholm), Estland (Tallin), Lettland (Riga),
Poland (Gdansk) and Denmark (e.g. Kopenhagen). Even Norway (Oslo) and
Great Britain (London, Harwich, Dover) may be included. Germany is
usually part of the trip, too (Bremerhaven, Cuxhaven, Hamburg, Kiel
and/or Warnemünde). Some cruises use the Kiel Canal (Nord-Ostsee-Kanal),
a small canal that connects the North and the Baltic sea. About 100km
long and built 1887-1895 it's one of the busiest world-wide. Depending
on the size of your cruise ship and day, you might see quite some
spectators along the canal.

See http://www.kreuzfahrt.buchung.de/rei...?region=Ostsee for
some examples (use http://babel.altavista.com for a translation).

This part of Norther Europe is best visited between May and August.

Regards,
soenk.e