I had a month's break between jobs last year and even though I knew I had a job to go to in a few weeks, having to sign on was a deeply unpleasant experience. I don't think many people do it through choice.
Occasionally (such as in the area of public libraries) volunteers do take jobs away from paid staff (though they have little choice if a library will otherwise close) but in most cases they do roles that would never be paid (such as marshalling a race!)
There's one reason to do a ladies-only race if you are any good - you might actually win it! Whereas in most races even if you are good you won't, though I think a lady may have won the Farmham Pilgrims marathon last year but such instances are fairly rare unless an elite runner sich as Liz Yelling turns up. I've made this point before on here, but I was 9th lady at the Fleet 10k last year but about 150th overall. This morning I was 84th at my local parkrun but 7th lady. So it is quite nice to do an event where you actually come right up in the front finishers (I was once 15th at a ladies-only race of around 600 participants). Even at a charity race where I was 3rd lady I was 45th overall! However, if ladies-only races were discontinued I wouldn't particularly care though I don't agree with Alan that they've had their day - the Windsor 10k last week had around 2000 entrants (and probably would have had a lot more if it hadn't been so expensive - £22 compared with the £12ish I paid for the Shinfield 10k the same day), the Glasgow 10k has around 12K entrants and there's a popular ladies-only race in Newton Abbot each September which is small but well supported.
I don't know why everyone gets so het up about Race for Life - if you are male, run another event or find a different charity to support - if someone doesn't want me, I don't want them.
Frankfurt's underrated as a city - there's quite a lot to do in the city and around the are - for example the Rhine Valley is only a short train ride away. Cologne is also in October - I did the half in 2011 and it's a well organised event and a great city to spend a few days in - and it's right on the Rhine and just up from the really scenic bit.
If I were choosing an autumn marathon in the UK I think it would have to be Chester (Loch Ness would also appeal and there are Jersey and Guernsey as well)
I'm surprised nobody has replied to this. I guess it depends on how much money you would want to raise, but Berlin sold out in about 3 hours so I am sure there would be interest in running it for you if you don't ask for too much money.