I just sorted the 51 ranked poker rooms based on difficulty of competition. My three favorite rooms (Bellagio, Wynn, and Venetian) are all in the top seven in terms of difficulty with respect to competition. No wonder I'm only a break even (roughly) poker player in Vegas, lol. Worse yet, the room I haven't played in but want to try is the Aria poker room which is also in the top seven at #2. My experience with the Bellagio, Wynn, and Venetian would put the Venetian as the toughest and the Bellagio and Wynn as similar. Now I only play $1/$2 NLHE (ok, $1/$3) with a little $4/$8 Limit O8 mixed in and I haven't been uncomfortable at those 3 locations but it makes me wonder if I should give up going to the nicer rooms and try the places reputed to have easier competition. Probably won't though. I enjoy the nicer rooms.

One thing those rooms you like have in common is that they don't take a jackpot rake. Jackpots take money from the hands of good players and put it in the hands of bad players, so good players tend to play where there aren't any jackpots.
Another factor is that the rake at those places is somewhat lower than at the other tourist rooms on the Strip, especially CE (formerly Harrah's) properties, which rake $5 on games where other properties rake only $4. Paying $6 ($5+$1) to the house vs. paying $4 is a huge difference, even in the short run. A lot of good players say that the weaker opposition in the higher-rake rooms compensates for the higher cost. This seems dubious at best to me. That $6 gallon of gas had better be REAL good for my car if I put it in my tank instead of the $4 stuff. Furthermore, the game selection at the rooms you mention is pretty good, so I have usually been able to find a weak game there eventually.

Green, all good points and I have to agree with you. I have played quite a bit at the Venetian but recently have played primarily at the Bellagio and Wynn on trips to Vegas. The $1/$2 and $1/$3 NLHE games have been good games at those locations. I'm the first to say I'm no poker pro but I haven't found it necessary to avoid those rooms due to the level of competition. Now some of the reason those rooms may be rated as tougher than others may have more to do with higher limit games.