NASA's manned space missions have been rather lackluster lately but one area where NASA has been very successful is with its recent deep space missions.
The Voyager missions took advantage of a planetary alignment that only happens every 175 years. It would be nearly impossible to do the same thing until the planets line up like that again. A probe wouldn't be able to hit all the outer planets at once, it'd have to select just one or two planets to visit.
NASA has had other successful missions to outer planets. The Cassini mission spent 13 years studying the Saturn system and ended just a couple years ago in 2017 when it was deliberately plunged into the planet.
The New Horizons mission was the first probe to study Pluto and then just a short while ago studied another Kuiper Belt object, now the most distant object ever visited by a space probe.
The Juno space probe is currently studying the Jupiter system. The ESA (European Space Agency) is planning another mission to Jupiter within a few years to study the moons. NASA will then follow that up with the Europa Clipper mission (set to launch in 2023) which will study Jupiter's moon Europa, which is an icy moon believed to contain a liquid water ocean beneath the ice.
There are several ongoing missions on and orbiting Mars. There are also probes that have been studying asteroids and comets and the Moon. There are also probes studying the Sun including the Parker Solar Probe which was launched last year and is en route.
As far as telescopes go, the James Webb space telescope, will be many times more powerful than Hubble, and is supposed to launch in 2021. There have been other telescopes, such as the Kepler space telescope, which has found literally thousands of exoplanets (planets orbiting other stars) and the Chandra telescope which studies the x-ray spectrum of the universe.