There is no single best half marathon — there's the best one for what you want out of it. A runner chasing a personal record, a runner planning a long weekend away and a runner ticking off states will each pick a different race from the same list, and each will be right. Decide which of those you are for this race, and the shortlist writes itself.

First, decide what this race is for

• A PR race is chosen for the course and the conditions. Everything else is secondary.
• A racecation is chosen for the place. The race is the anchor for a trip you'd enjoy anyway.
• A 50-state race is chosen for efficiency: the right state, on a weekend that works, with the least friction.

You can combine two of these. Trying to get all three from one race usually means compromising on the one you care about most.

If you want a personal record

Fast half marathons share a handful of traits. Look for as many as you can find in one race:

• A flat or gently rolling course. Read the course description before anything else. Short rollers are fine; long climbs in the second half are not.
• Be careful with big net-downhill courses. They can be quick, but sustained descents are hard on your quads. If you choose one, train on downhills first.
• Cool, calm weather. Temperature is the biggest factor you can't train away. Favour months and places where race morning is reliably cool, and avoid exposed, windy courses.
• A field to run with. A few thousand runners means there will be people at your pace the whole way. Very large fields can mean a crowded first mile — check whether the race uses corrals or wave starts.
• Few sharp turns. Out-and-backs with a single turnaround and point-to-point courses are generally quicker than routes that twist through a downtown grid.
• Simple race-morning logistics. A late night, a long shuttle and a cold hour in a start corral all cost you time before the gun goes.
• A certified course, if you want the time to count for anything official.

On RaceRove, each race page shows the course notes from the listing, typical race-day weather and a PR-potential estimate where there's enough data to make one. Start from the national half marathon list, or go straight to a state with plenty of flat terrain to choose from, such as Florida, Illinois, Indiana or Texas.

If you want a racecation

Here the question flips: would you take this trip even without the race? If yes, you've found a good one. Then check that the race won't spoil the holiday.

• Pick the place first. Coastlines, national parks, wine country, a city you've always meant to visit — the half marathon is the excuse.
• Run early in the trip. Race on the first morning or two, then enjoy the rest of the holiday on tired legs rather than saving yourself all week.
• Respect the travel. Long flights, time-zone changes and altitude all affect how you'll feel on race day. Arrive at least a day earlier than you think you need to.
• Look at the whole weekend. Expos, shake-out runs, shorter races for family members and a finish-line party are what turn a race into an event.
• Lower your time expectations. Scenic courses are rarely fast ones. Decide in advance that this one is for the views.

Destination-friendly places to start browsing: half marathons in California, Hawaii, Colorado, Florida and Washington, DC.

If you're counting states

The half marathon suits a 50-state project well: it's a real effort in every state without the recovery cost of a marathon, so you can race more often. For these races, efficiency wins.

• Choose by calendar and geography. The right race is the one that fits a trip you're already making, or that pairs with a neighbouring state on the same weekend.
• Favour easy logistics. Smaller races with race-morning packet pickup and parking at the start are ideal when you're flying in the day before.
• Do the scarce states first. States with short race calendars leave you fewer options, so plan those around specific events.
• Don't race every one. Treat most state races as steady runs and save the hard efforts for two or three a year.

The 50 states hub lists every state with its current race count, and How to Run a Race in All 50 States covers the planning in detail.

Give yourself enough time to train

Count backwards from race day before you register. Many half marathon plans run for roughly 10 to 14 weeks, and that assumes you're already running regularly when you start. If the race you like is closer than that, either adjust your goal for it or pick a later one. The app's training countdown shows how many weeks you have and where a build would need to begin.

Compare your shortlist

When you're down to two or three races, score them against the goal you chose at the start:

RaceRove's compare tool puts up to three races side by side, and the race match quiz will suggest races from a few answers if you'd rather start there.

Red flags before you register

• No confirmed date. If a listing only shows the month the race is usually held, wait for the organiser to announce the date before booking travel.
• A vague course description. If you can't tell whether it's flat, hilly, road or trail, ask the organiser or look for a course map.
• A registration cap or lottery. Popular races sell out. Know the opening date and have a second choice ready.
• No transfer or deferral policy. Injuries and diary clashes happen. It's worth knowing your options before you pay.