Tiffany's has a nice gift guide, with many surprisingly affordable options.
For example, this Elsa Peretti Color by the Yard necklace in sterling and aquamarine is a quite reasonable $125.
Tiffany Key Pendant, 2" long in sterling silver, $175.
Tiffany Snowflake earrings in sterling silver, $175
A gift in the Tiffany blue box is always nice...
On the silver topic... What better way for a Gucci girl to combine her love of all things bamboo with sterling silver? The answer is Tiffany's Bamboo Sterling Silverware! I'm not sure if normal people still think it is necessary to have sterling silverware, personally I think it is de rigueur. 
Side note, they used to make bamboo jewelry also, as part of the Tiffany Nature collection but sadly, it was discontinued. I have the bamboo hoops that weigh a ton (uggh) but look great!
Diamonds are a girl's best friend, but it's good to mix things up right? I was recently given the Elsa Peretti Teardrop earrings and this gift has caused me to have a Tiffany sterling renaissance. 
I dug out my collection and polished it up and (re)realized that I LOVE this stuff. I'm not sure why I hadn't worn any of it in so long. (okay maybe because it's annoying to have to polish it, more on that below) Tiffany's designs are so classic. My favorites are the Atlas collection
, the Peretti bean 
and the Peretti teardrops. And buying them in sterling makes them affordable to most people... although "affordable", it is kind of an outrage when you consider how much 925 silver costs (its dirt cheap), the markup Tiffany has is INSANE. But hey, they have to pay for the nice blue boxes and their designers, and for some really expensive real estate.
Frank Gehry even has a line now! Tiffany's calls it "a bold new vision of arresting shapes and forms". I guess that's what you'd expect from the man who designed Bilbao [Guggenheim]! I like the Torque line. 
(3 pendants in that collection at left) He's also doing some bone china bowls and vases that are really cool. 
Note to guys everywhere: if you don't know what to get your girlfriend/wife/mistress etc. you cannot go wrong with something from Tiffany's. (note of caution - do NOT buy Tiffany on Ebay, it's most likely FAKE and made in China)
Oh, last quick note on polishing sterling... I learned this a long time ago. Take a pan and line it with aluminum foil, boil some water and get out some baking soda. Put your jewelry items in the pan on the foil, pour hot water over it and dump in a few teaspoons of baking soda. It will fizz... let it sit there for several minutes then take your stuff out and buff it with a soft cloth and it's like new! This works if the tarnish is not really bad - if it's really bad then you can do this, but you'll need to use silver polish too to get all of the tarnish off. Don't use this method on soft stones or pearls though!