Vega, magnitude 0.03, 25 light-years away, and the fifth-brightest star in the sky. It looks like an ordinary white star and is not: it spins once every 12.5 hours, at 88% of the speed that would tear it apart, so it is squashed into an ellipsoid with a 2,000 K temperature difference between its equator and its poles. We see it nearly pole-on, which is why it took interferometry to notice.
23.9° north-east: Deneb, the Swan's tail, magnitude 1.25 — and nobody can tell you how far away it is. Its parallax is smaller than the uncertainty on the measurement, so the published range runs from about 1,400 to 2,600 light-years. Take the middle and Deneb is radiating something like 100,000 Suns. It is the most luminous star most people ever look at, and it is faint only because it is absurdly far.
34.2° south of Vega, Altair closes the triangle — 16.7 light-years, magnitude 0.76, and the first star other than the Sun to be photographed as a resolved disc. It turns once in 8.9 hours and is 22% wider across the equator than pole to pole. The same physics as Vega, seen edge-on instead of face-on.
The whole figure: sides of 23.9°, 34.2° and 38.0°. It is not a constellation — the three stars belong to Lyra, Cygnus and Aquila — but it is the most useful shape of the northern summer, because the Milky Way runs right through the long side. Deneb sits in the stream; Altair sits on its bank.
Under a dark sky, look at the Milky Way between Deneb and Altair. It is split lengthwise by a dark lane — the Great Rift — which is not a gap in the stars but a chain of dust clouds a few hundred light-years away, blocking the light of everything behind. You are looking down the length of our own spiral arm, and at the soot in it.
Follow Cygnus 22.3° from Deneb down the neck to Albireo. Any telescope splits it into gold and sapphire, and it is the standard answer to "show me something pretty". Awkwardly, Gaia's astrometry says the two stars are moving too differently to be orbiting each other: after two centuries as the textbook double, Albireo is probably a coincidence.
Halfway between Sheliak and Sulafat, the two stars at the bottom of Lyra's parallelogram, sits M57 — the Ring Nebula. It is a dying Sun-like star that has shrugged off its outer atmosphere, now a smoke ring 1.3 light-years across and magnitude 8.8. A 75 mm telescope shows it as a tiny grey doughnut. This is roughly what the Sun will do in five billion years.
Vega passes within 2° of the zenith from 40°N — it is almost exactly overhead — so the Triangle dominates the whole upper sky from June to October and does not so much rise and set as tip over. Note how late it stays useful: Deneb is still up when Orion arrives.