It really depends on what you will be doing (not sure where the Indy race is held) and your transportation, as well as your budget.
We've always had decent accommodations (frequently much better than decent!) at Flamingo (stayed there a dozen times or so for conventions/conferences), Bally's, Monte Carlo and Mirage. Excalibur has been very good and not so good--last time we stayed there the entire ground floor became a very loud club at night. Not my style! Rooms were okay though. Just be sure to book a refurbished room--the old ones are very tired.
Flamingo, Bally's and Mirage are mid-strip. Excalibur is south (only Luxor and Mandalay Bay are farther south); Monte Carlo is just a bit north of Excalibur (same side of the strip).
Apart from The Venetian and Wynn resorts, most of the properties on the Strip are owned/operated by MGM-Mirage (may have changed the name, but MGM will get you there) or Caesars. Not precisely true, but the ownership/operations have consolidated from half a dozen or so to the two major management companies--they can control the rates much better.
You also can check out the options for downtown Las Vegas (Fremont Street area). We don't stay there (BFF and I), as we're too middle-aged females, but many people we know do enjoy it. If you stay or visit Fremont Street, be sure to have breakfast at the coffee shop at the Golden Gate Hotel & Casino located at 1 Fremont Street. It's served 24 hours a day. It's our favourite place for pancakes--and everything else we have tried has been good, as well!
Las Vegas Convention and Visitors Bureau is a good site for general information about the area and less biased toward specific resorts, for the most part.
If you don't particularly want to stay on the Strip or at a casino resort, most of the major chains are represented in the Las Vegas area, with varying levels of service and condition. Check the websites for your favourite chains, then tripadvisor.com or your favourite website for comments and mapquest.com for location.
October can be a lovely time to visit the Las Vegas area. It is high desert, so days tend to be quite warm (sunscreen, sunglasses and hats/caps, please!), but evenings are a bit cooler than the low desert where I live. The weather can be a bit variable, so prepare to layer clothing, if necessary.