As for selling, I really feel such improvements will NOT increase the value enough to cover the expense at this time but with such improvements, it will most likely be the first to go under contract.
There is one recent example where a unit sold that was in horrible condition for "say" "150k" and another unit sold for "165k" with major upgrades. I doubt that the horrible unit could come up to the level of the other for 25k!!! The horrible unit went under contract before the great unit came on the market otherwise I am sure it would still be available!
Agreeing with Dp's comment "an updated will often sell for more than one that hasn't been updated, " understand that updating that kitchen or bath may not necessarily net you 100% return on your update investment (see NAHB's annual Cost vs Value reports), but help faciliate a quicker sale.
An inspector, appraiser, and/or GC should be able to give you a good idea of what you need to spend, and they should also be able to help ensure that you don't overspend (on stuff that really won't add much value).