God is an Astronaut is quite unique in the fact that they rely on instrumental compositions in their post-rock. It is pretty much impossible to find something that follows in the same vein, although I know a few that are close.
Ef, one of the veteran bands of the post-rock scene has made a few almost instrumental songs that sound like God is an Astronaut, if the band members were younger, more fragile, introspective and wrote all their songs on rainy days.
Here is the most fitting song: (Note, it stops being instrumental at around 5 minutes)
Year of No Light, a French band mostly relying on guitars for the grandiose atmosphere that they produce. Their song Perséphone is long, dreamy and full of splendour.
Thränenkind is a German band, normally known for their post-black metal have also made a instrumental piece which is definitely worth a listen. It is a very slow journey and quite anticlimactic, so save it for a rainy day.
Other bands worth mentioning:
Ethereal Beauty, especially with their song "The Sun Shines Tomorrow"
Explosions in the Sky, pretty much any of their later work.continuous development cities skylines mods finding an investor for new products development of an technological research motion key digital entrepreneurs types of motivation ppt lagos jewelry bracelets man development cities in georgia usa applied developmental psychology jobs fintech fund startup media citie skylines twitter four motion trade fintech ltd the all new city 1 liner inspirational quotes the how of motion work in motion encourage empowerment quotes box startup website entrepreneurs people and development best pc games with a real life city man in motion motion work city of very fintech etf fidelity fintech books middle-market inspirational quotes about life and death find private investors in india fintech studies startup images startup team vacation in ma i am in vacation entire summer startup sale cities in alabama in alphabetical order american venture capitalist chicago fintech fintech companies california development of christmas vacation room best startup time of city vt fintech incorporated towns of va vacation more men development innovative technologies s and s motor vacation night how to find investors for small business start up banker motion photo body motion city 2014 women in development motion share lagos business school address developmental milestones 4 months old having a vacation entrepreneur how to global companies in your city own this city entrepreneurs of 2012 information technology companies in houston oil entrepreneur fintech australia inspirational quotes for students in school city m o fintech 250 fintech world ceo types of entrepreneur entrepreneur best cities in virginia that start with s kid entrepreneur most impacting quotes photo startup what cities are close to cleveland ohio cities in pennsylvania start-up companies the city below vacations for couples over 50 development now language development stages piaget entrepreneurship meaning development in the news the city o motion is life 2013 vacation dorm room quote decorations time and motion vacation young startup product do motor vacation form vacation post developmental psychology programs set startup programs windows 10 what motor developmental pediatrician autism near me internet entrepreneurs vacations band city world starting first business water entrepreneurs initial development top pinterest inspirational quotes what to know on a train vacation aarp night motion how to startup fintech stock ticker the best entrepreneurs what is life development cities in virginia that start with r not in our city civic leader startup king social events 6 motor motion web city fintech advanced technologies what was new york called little entrepreneurs my own city home development developmental milestones 2-4 years m t development entrepreneurs program small business ideas for small towns in tamilnadu city state service development technology innovation all motion cities in michigan that start with s sharing economy not in the city socioeconomic development vacation state fintech kenya developmental stages of babies 0-3 months inspirational quotes about life carolina fintech the city above development music state and development startup accelerator washington jobs this is for my city out here in the city book a vacation fintech ideas