What you're actually paying the 'service' for

The real difference between a serviced apartment and a holiday let is having someone to call. The let gives you keys and a host who replies when they can, and the serviced apartment gives you a building with staff in it. Five services do most of the heavy lifting, they're nowhere near equally common, and it pays to work out which ones your stay depends on.

The front desk and the concierge

Start with the front desk, because everything else tends to run through it. Reception takes deliveries, holds keys, books cars and sorts out the shower that packs up at 7am. About half the residences we list have one, and fewer staff it overnight, so if you're landing late or want someone on site through the night, ask specifically. Cheval Hyde Park Gate in Kensington, for instance, says on its own website that its front desk runs 24 hours, which is what to look for on a family stay or a long work trip.

A good concierge saves you evenings of research, and the useful requests are specific: a table for four on a Saturday where the chef will do a vegetarian tasting menu, two seats for a West End show on a night that looks sold out, a car to Heathrow Terminal 5 at 5.30am. Ask something vague and you'll get something vague back. Quality varies more here than with any other service. Some buildings have a proper team with good restaurant contacts, while others send you to the front desk, which will do its best with a search engine. Test it before you arrive with something small, like a restaurant near the apartment for your first night, and the speed and precision of the reply will tell you most of what you need to know about the rest of the stay.

Housekeeping and laundry

Daily cleaning is rarer than people assume. Only about a fifth of residences mention a maid service, and plenty of the rest clean weekly or at checkout. For most stays of a week or more, weekly housekeeping with a linen change is plenty, and daily matters mainly if you're entertaining, travelling with small children, or just can't face loading a dishwasher. Extra cleans can often be added for a fee, and it's best to book them at the start of the stay, because housekeeping rotas fill up.

Most apartments have a washing machine, and lots have a washer-dryer, which is fine for socks and gym kit. Shirts and suits are another matter, and a residence with a pressing or dry-cleaning service saves a business traveller an hour a week hunting for a dry cleaner that's open when they aren't working. Fewer residences list laundry than you'd expect, and the ones that do use the word loosely, so check whether it means a machine in the flat, a shared laundry room or a collection service.

Private dining, and what to ask

A kitchen gives you a third option between eating out and room service: a private chef who shops, cooks and clears up in your apartment. That suits a working dinner you'd rather not hold in a restaurant, or a family night in after a long day. The residence may have a chef it uses regularly or may point you to an agency, and either way it needs a few days' notice at least, more for weekends. The simpler version is a grocery delivery before you arrive, worth asking about for anything longer than three nights.

Add these to the notes when you send a request, since they go straight to the residence's reservations team.

• Front desk hours: 24 hours, or daytime only
• Housekeeping: how often it's included, and what an extra clean costs
• Laundry: a washer-dryer in the flat, and whether shirts can be pressed
• Concierge: whether it books restaurants and theatre or only recommends
• Groceries: whether a delivery can be taken in before you arrive