As far as an e-reader goes, you can't compare an e-ink screen to an lcd screen for reading. E-ink screens looks almost exactly like paper, as opposed to lcd screens. And with the cheapest Amazon e-reader being $79, you can't go wrong with it.
-As far as tablets go, I would suggest NOT getting the Nook color for one big reason, hardware. At $150, you would only have an 800 mhz processor (0.8 Ghz) and only 512mb Ram (though this isn't a HUGE issue). The limited processing power MAY be enough for what you are asking (maybe NOT gaming and movies but ok for e-reading and LIMITED browsing), but when something more than twice as fast is only $50 more, it is definitely worth it in my opinion. This is a reason why I would stay away from Coby's tablets as well, hardware outdating. For $50 more, you could get the Acer Iconia tab a100 on Black Friday as well as a few other tablets.
-The Iconia tab has a 1Ghz dual core (2Ghz total prosessor power, more than twice that of the nook color as well as twice the ram) However, this would be another tablet I would suggest staying away from if you need battery life. I have heard it lasting as low as 3.5 hours and it will only decrease with time.
Now for what I DO suggest:
-Look at the Blackberry playbook for $199 on Black Friday at staples. It's the same price as the Iconia tab, has the same specs (1Ghz dual core and 1 GB (1024mb RAM), but the battery life will last a lot longer. Yes, it doesn't run android BUT Blackberry said that soon, they will have support for the android market and even if they don't, they should have enough to keep one busy. Also it has the best camera on a tablet that I have heard of.
-You could look at the Fire for the same price if you can't get anything at Black Friday, but if you have the chance to get it, I would go for the playbook over the Fire mainly because the Fire doesn't have cameras, only has half the ram and you are stuck with the 8gb space and a limited choice of connectivity (for example it doesn't have HDMI out).
-Also, if you don't get to do Black Friday, the Nook Tablet is a good tablet to look at, though still the Blackberry has better hardware (a camera and more ports). If you don't get to do Black Friday, this would be the best tablet to buy at $250 or under because it has a dual core 1Ghz and 1GB ram (1024mb Ram)
-However, if you DO do Black Friday and you are going to Best Buy, it is definitely worth it to look at the 10.1 inch screen Asus EEE pad Transformer for $250. It is probably THE best tablet in this generation of tablets (minus the camera. The transformer can record video in 720p, the Playbook can record at 1080p). Still the is the BEST you could get for the price overall on Black Friday unless you are dead set on a 7 to 8 inch screen.
These are what I believe are the best tablets out there for the holidays. There are others that are just as good or close, but they are out of your price range and won't come down to it for Black Friday as of now. Keep in mind, I DO NOT own any tablet myself. I am telling you what I have heard from reviews since I am also looking for tablets in your price range (actually I have been looking for a year, but thought Black Friday would be my best bet. I have been very patient

. I would look at reviews for each of these tablets mentioned and then you can compare.
As for Wifi, as long as you get a well known tablet brand, you should have no problem in this area for any tablet. All "well-known" tablets will have wireless n, while others will have wireless g. Wireless n is much faster and can go further than wireless g (as long as your wireless router is wireless n. If you router is wireless g, your tablet will only pick up the g signal whether it is wireless n or not). Even wireless g isn't that slow. Generally, if your router is older than about 2 years, most likely it is wireless g (just some extra information. It's not always the device that is the problem

Here is some more information on the different types of Wifi connections if you want to go into this further:
IEEE 802.11 - Wikipedia, the free encyclopedia (The full name of these bands are 802.11g and 802.11n)
In short, the best 7 inch tablet you could get would be the Blackberry Playbook and the best 10 inch tablet would be the Asus eee Pad Transformer (all in my opinion).
Other notable tablets to look out for a price drop are:
Acer Iconia tab a500
Asus eee pad Slider
Apple Ipad 2 (though an unlikely price drop)
Lenovo IdeaPad Tablet K1
I hope this helps!