Death of the Necromancer by Martha Wells has a solid mystery/revenge plot, with some quiet romance and solid friendship and interesting world-building. Although to warn you, there's a fair bit of crawling around in the sewers and the necromancy is pretty icky. Her other books are all good too--she has the opening chapters to each available on her website, as well as some short stories.
Something Wicked This Way Comes by Bradbury is hard to pin down, but a definite classic--all about choices and growing up and reeeeeally creepy traveling carnivals.
Jonathan Strange & Mr. Norrell and the Ladies of Grace Adieu, both by Susanna Clarke, are fantastical history or something--the first is a very slow but interesting novel (well, if you're fond of pseudo-academic footnotes), and the second is all short stories set in the same world.
The Human Edge by Gordon R. Dickson is one of my favorite SF short story collections--pretty much entirely about humans (all guys, alas, but to be expected given the era) being dangerously underestimated by aliens (and sometimes other humans). By turns hilarious, sobering, and rollicking good fun. The Wolfling and The R-Master are longer looks at the same theme.
Lord Darcy by Randell Garrett is a collection of mysteries set in an alternate history where there's magic and Richard the Lionheart managed to sort out the succession properly and keep John off the throne. No real romance, but some good mystery-plots and fascinating world-building.
Then there's pretty much anything by Diana Wynne Jones--Deep Secret is one of my favorites, but they're all good.
Robin McKinley is pretty hit-or-miss for me, but I do like Rose Daughter and Spindle's End very much. Some lovely romance, which is not something I say often.
The Abhorsen trilogy by Garth Nix is another favorite--I love the idea of a reverse-necromancer, someone who goes around laying the dead to rest whether they want to go or not.
For some more SF, Andre Norton's Solar Queen series is a fun change from the usual space opera--think Firefly, but without the angst and smuggling and stuff. Plague Ship and Voodoo Planet are available on Project Gutenberg.
And if you haven't read any of Terry Pratchett's Discworld books, do. I'll happily tell you where to start and what order to read them in. One of my favorite series ever!