I have a real dilemma as I work on my next book. Sources and research aren't an issue, if you stick to English Regency you can find almost everything from a guidebook to London to the list of attendee's at the Duchess of Richmond's ball on the night before Waterloo.
No, the problem is how much sex do I put in? Real regency period writers put in almost nothing, and left everything to the reader's imagination (but then nights were long and there wasn't much to do, so a good imagination was a necessity). Only fast women held hands before marriage in the 1810's. I'm pretty sure Mr. Darcy and Miss Bennet don't even hold hands in Pride and Prejudice. More recent, but still relatively old, authors like Georgette Heyer had a little bit - things holding hands and kissing that would have been considered almost as bad as fanny hill during the regency - but nothing you wouldn't let your daughter read.
Today books run all the way from fairly tame to baring it all. I have to figure out where my voice fits in that picture.