Hola,
La verdad es que si estás una semanita... yo te recomendaría alojarte unos días en Ubud, de ahí hacer todas las excursiones "culturales" y después tienes Seminyak que es un poco pijito con playas chulillas y Kuta que es más rollo mochilero/surfero/putero con una playa enorme con olas gigantes.
A mi me gustó mucho, además está bien de precio (caro algún alojamiento pero son espectaculares).
Las islas Gili (jeje) son para estar en plan solitario, solo hay playa y nada más, es para alejarte del mundo. Si vas solo una semanita igual no merece la pena.
Disfrútalo!!
EDIT:
Te adjunto información que me habían dado cuando fui en su día:
1. Sunset Dinner at Jimbaran Bay.
Wikitravel:
http://wikitravel.org/en/Tanah_LotThis is an absolute must do in my opinion. Dinner at Jimbaran Bay during sunset, assuming the weather is good(meaning it's not too cloudy), is probably one of the more romantic experiences you can have in Bali. Sometimes there'll be this String Quartet that walks around and serenades you.
2. Sunset at Uluwatu
Wikitravel:
http://wikitravel.org/en/UluwatuUluwatu is one of the more beautiful places in Bali. I got there a little later than I would've liked. I arrived at about 6:20pm so I didn't get to really see much of the temple during sunlight. But the Traditional Kecak Dance performed during Sunset is simply magical. It's an experience not to be missed. You will truly understand why people feel that Bali is such a mystical island.
3. Tanah Lot
Wikitravel:
http://wikitravel.org/en/Tanah_LotI don't have photographs from Tanah Lot because I didn't bring my Camera.
Tanah Lot is beautiful at Sunset but... legend has it, there's a curse. If any couple that goes there that is not yet engaged they will split up soon after. Personally, it might be a coincidence... but I've seen quite a high proportion of my friends split up soon after returning from Bali. It is most spectacular at Sunset, but I understand you guys have limited Sunsets so this one is not high up on the list. =-D
4.Ku-De Ta
Perfect for after-dinner drinks sitting by the beach and listening to the sound of the cascading waves. Ku de Ta is located on an idyllic beach in the Seminyak area. It's one of the most famous bars/restaurants in Bali.
Website:
http://www.kudeta.net/5. Quintessential Balinese Tour
This normally takes the entire day so you may or may not be able to fit it in. Try calling my driver Mr. Ketut Astika at +62 81 2397 2131 and he may be able to help you. Try calling him today if possible and making an appointment, possibly for Saturday or Sunday. Tell him you got your number from xxx who is a friend of xxxx from Singapore.
What happens normally is you watch a traditional dance early in the morning, then make your way(while stopping at handicraft stops of various mediums like Batik, Pewter and Wood Carving and stuff like that, some of which is quite interesting, some of which, not quite) to Kintamani where you will have a buffet lunch while enjoying the view of Mount Batur. On the way down, you will see the rice-terraces before you stop at Ubud where you can find Monkey Temple and Monkey Forest. In Ubud there is an Arts Market so you'll get to take a good look around. =-D Hopefully this tour should end by 4, at which point you can ask the driver to take you to Uluwatu or Jimbaran Bay.
Alright. That's about all bro... I hope you have a good time.