I use incandescent to get a warm glow, LED in kitchens and garages, clear bulbs to get sparkle and use the old style yellow filament bulbs to highlight a great light fixture.  

The original electrical would have been installed to run a few incandescent bulbs, a radio or two and perhaps an early appliance and was not designed to handle today's electronic demands.Another thing to keep in-mind, depending on when the property was converted to apartments, is that the conversion may not - quite likely will not - meet current fire codes, which will both impact your insurance rates and your renovation costs when you do undertake a substantial rehab.That gorgeous exterior, with it's clapboard/shakes (or era brickwork) and elaborate trim will be high maintenance - that does not mean it's not "worth it", just that you need to budget accordingly.Personally, I enjoy performing deep energy retrofits on these old buildings (which can be very solidly built), but it can be an involved and costly experience, hence we are always looking for the unloved and run-down which can be purchased cheaply.If that house has been 200+ days on market - and no other landlord or investor has touched it - tells me there is a problem with the value proposition of the deal.  

LED light bulbs are incredible, in my opinion the same as or even better than, the old school incandescent ones.I got mine at a special sale (I think it was at a Home Depot) a while back, they were something like $8 or $10 each.

Bellingham's housing market is SMOKING STEAMING INCANDESCENT ABOUT TO ACHIEVE NUCLEAR FUSION HOT with housing prices jumping 11%...LAST MONTH.  

You could maybe cut that cost by making one of those lights a motion detector, but I think that a full time florescent bulb is going to be cheaper to run than turning an incandescent or mercury vapor off and on.I've got a dusk to dawn florescent security light that is 14 watts.

LED/CFL and even Halogen light bulbs are more efficient than incandescent lighting.

If you want to replace a regular one then just remove the old/regular one and install the new dimmer one.Nut remember that you can't use a dimmer switch with fluorescent bulbs, they only work with some LED bulbs and incandescent.  

One other thing you may want to consider is to switch all appliances to energy efficient models, switch light bulbs to CFL or eco-incandescent bulbs. 

  :) If they are still running incandescent lamps, you can buy a little headroom quickly by switching to LED. 

I sent the tenants an email that I wanted to come over for a regular maintenance visit, and they mentioned the burned-out bulb; I brought another one and swapped it while I was already there for other things.The bulbs that burn out the most on me are the incandescent globes over the bathroom mirror; I like the look enough that I haven't switched these to LED.