In attempting to assess the value of individual REITs, you and other investors are making the market in them efficient, so that "lazy" people like me can simply invest money in a broad-based collection of them like Vanguard's REIT index fund, knowing that we are eventually likely to make a decent return on the investment. So keep it up, and perhaps your diligence will net you a fraction of a percent extra gain (or perhaps not), but "free riders" like me will benefit either way.
In looking at "price to book ratios," it is important to understand how book value is calculated. The book value is simply the price at which an asset was acquired, minus depreciation as defined by the IRS. This "depreciation" often has absolutely no relationship to the change in the fair market value of an asset.
For example, a piece of raw land may have been purchased in 1980 for $100,000, and have a value today of $10,000,000. But its "book value" would still be $100,000. This huge difference is possible despite the fact that the value of land can't be depreciated.
Likewise, a commercial building might have been purchased in 1980 for $100,000, and have been depreciated such that its "book value" is now, say $10,000 (the 1980 value of the land that it sits on) even though it might have a current market value of $10,000,000 or whatever. Thus, an REIT with a high price to book value may or may not be a good value.