Hi again
For both ith is nice that you took the other extensions too, a package is IMO always easier to sell then only one extension. (of course depends on the domainname

)
(pssst... a hint "Premiumletting.com" is avaliable, not that you should reg. it, just saying.)
IMO when I reg. and I cant afford to reg. all avaliable extension, then I would rather have both plural and singular .com, then only plural or singular .com and .net.
Premiumlettings.com .net .co.uk
Positive:
- letting is a term only used in UK (
letting=renting/leasing,
premium=very high value; if this is wrongly understood please correct me)
- niche, good value keywords
- as I understand it "letting" is really popular in UK in the moment.
- property market, and especially the high-value property market, is a good market

- recognizable for the end target group (ex. the property owners)
- easy to remember, pronounce and spell
- companies who do business in high value letting, would be interested.
- brandable
Negative:
- only targetable the UK market. (not that this is only bad. its in the negative field cause its country specific and not world wide. In some cases it doesnt hurt the value, like in this one, and sometimes its even better to be as specific as possible.)
Appraise: You have to find the end-user to get high value for this. If you find the right buyer low to high $x,xxx for the bundle; maybe these are interested:
"Key Properties UK Ltd" or similar companies
Premlet.com .net .co.uk
Positive:
- short
- easy to pronounce, remember and spell
- brandable
Negative:
- as I know it not a word, but a made up word, doesnt mean anything.
- is not recognizable.
Not much to say to this one really. (If this is a term in UK, unknown to me a non-brit, it might be more valuable.)
Appraise: reg. fee