I have newly renovated 1920's home that has freshly sealed hardwood floors.

If your old roof is sealed up, you can insulate on top as you have a new attic space.

If a sealer is applied after the cleaning then you will save the grout color for a few years longer than if you don't seal.

@Scott Lewis - as a past contractor who dabbled in energy efficiency in housing I'd say look at insulation, air sealing and mechanical (HVAC, water heater) upgrades prior to solar.

Exterior faucets (hose bibs): Re-seal all around base where attached to the wall, front and back yards3.

i think keeping a home warm has lot to do with insulation and keeping drafts sealed as well as the heating system applied.  

In such a context, it may not be expensive at all - we've had payback in as little as three years.To air seal ductwork - which is arguably more important than insulating - you can use appropriately rated ventilation tape (foil-based or other) or mastic.  

If its a matter of sealing maintenance on the granite and you're debating whether to go with a quartz or corian, then thats a whole other discussion.Seems like overkill for a rental even at the high end.

You will need to seal every surface with a shelac primer/sealer in order to get rid of the smell.  

I would do it that way, I have let my friends do letters for me certain weeks where I couldn't do them but I trusted them to not screw up because some people can screw things as easy as letters; sealing and stamping.