On My TBR shortlist and a question

It's no secret that my TBR pile has long since passed "pile" and is now "cases."

Fighting for top spot at the moment are:
The Surrender of a Lady by Tiffany Clare

-I've been slavering over this one since I first read a blog by the author discussing the premise. Heroine sold into a harem to cover her late husband's debts and having the experience make her stronger? :makes grabby hands:

Scoundrel by Zoe Archer

This is the second installment in her Blades of the Rose quartet, preceded by Warrior. While I am not normally interested in paranormal romances, these read more like adventures than paranormals, strictly, and the promise of an Indiana Jones style read and exotic settings caught my interest. Also will have to hunt down her entry in the anthology Half Past Dead.

A Season of Seduction by Jennifer Haymore

- I am a sucker for a Christmas set story where emotions run high. Since the prior two books in this expanded Regency era world had lots of angst and tangley hearts, I'm betting this will as well. Is early October too soon for a Christmas book, though?

Of course, any of these can get tossed by the wayside to wait their turn as soon as I get my mitts on The Border Vixen by Bertrice Small. Since my birthday is in October and there's always a new Small historical in October, that's my traditional gift to me (though if family members want to beat me to it, by all means, do. )

Since one of the exercises I have in my From Fanfiction to Fantastic Fiction class involves spotting common threads, the first thing that came to mind with the above is that all are linked to other books. Even the debut title. I've had several reader friends ask me if I know of any currently published historical romances that are not in series, and that's making me go "hmm."

So far, I have four titles in electronic release and none of them are linked in any way. All are in different times and locations. That reflects my reading preferences as well. If a book is all on its own, no spinoffs, sequels, prequels, companions, etc, that will catch my attention faster than a book that's linked to something else. This sort does seem to be in short supply these days, but with time crunchy for a lot of us, and the economy as it is, with book costs more than they used to be, there is also an appeal in being able to pick up a book and knowing one doesn't need a scorecard, family tree or a hunting expedition to pick up X, Y and Z' s "own book."

While much has been written on the appeal of connected books - being able to revisit what's already familiar is a biggie- I'm interested to see what readers like about trying something new. What makes a successful standalone to you?